Armitage shank toilet the water keeps running even when the float has been adjusted?

hi Patricia.
Overview Toilets haven't changed much in the last 80 years. After a flush, water still fills a tank, lifting a float that shuts off the water when it reaches a certain level. A lever still opens a flapper to cause the flush, falling back into place when the water level drops. So it's no surprise (nor any consolation) that we face the same flush problems today that our grandparents did. Sometimes the flush is too wimpy, sometimes the toilet keeps running, and sometimes the bowl doesn't refill.
Our ace plumbing consultant has a simple four-step strategy to solve 95 percent of these problems. You can complete the first three steps in five minutes. That'll solve most problems. The fourth step is usually easy too, but not always. More on this later. These steps work for most toilets but not for pressure-assist models.
Check the fill tube

Overflow tube problem

Push the fill tube firmly onto the fill valve. Make sure the fill tube sends water into the overflow tube.Remove the tank lid and find the fill tube. It's a small flexible tube that runs from the fill valve to the overflow tube. While the tank refills, this tube squirts enough water down the overflow tube to refill the bowl after the completed flush. If this tube falls off or the water stream misses the overflow tube, the bowl won't fill and your next flush will be wimpy (that is, won't develop a strong siphon). Reattach the fill tube and make sure it perches about 1 in. above the rim of the overflow tube. Flush the toilet and watch the water stream to make sure it goes down the overflow tube.
Adjust the fill height

Check the float

Adjust the float to set the water level. Pinch the clip and slide the float up or down on the rod. Keep adjusting the float until the water shuts off at the proper level.The water level in the tank is controlled by an adjustable float. A float that's set too low produces a weak flush; if it's set too high, water spills into the overflow tube and the fill valve won't shut off. The toilet keeps running. Look for the fill level mark on the inside back of the tank and mark it on the overflow tube so you can see it more easily. If you can't find it, measure down about 1 in. on the overflow tube and make a mark. Then flush the toilet and see if the water reaches and stops at that mark. If not and the toilet keeps running, adjust the float up or down. If you have an old toilet, you'll have to bend the brass rod that connects to the float ball to make adjustments. But with newer toilets you usually turn a screw or slide a clip along a rod. Flush the toilet after each adjustment.
Also make sure that the water level is at least an inch below the C-L (critical level) marked on the fill valve. You can adjust the height of many valves to raise or lower the C-L.
Occasionally the fill valve simply won't shut off, which means that it's defective. If so, turn the water supply off at the shutoff under the tank. Buy a replacement valve (sold at hardware stores and home centers). You don't have to match the old one; many, like the one shown, fit most toilets. It's a 15-minute change-out.
Adjust the flush handle/flapper chain

Flapper chain fix

Adjust the chain to leave a little slack with the flapper closed. Then cut off the excess, leaving about an inch.A chain that's too short or tangled won't allow the flapper to close and water will continue to leak into the bowl. This causes the fill valve to cycle on and off to refill the tank. A chain that's too long, or a flush rod that hits the the tank lid, won't open the flapper wide enough to stay open for the full flush. You'll find yourself having to hold the lever to complete a good flush.
To avoid these problems, adjust the linkage in the chain to leave only a slight bit of slack when closed. Cut the chain at the rod to leave only about an inch extra to reduce the potential for tangles. Then put the tank lid back on and make sure the flush rod doesn't strike the lid when you press the lever. If it does, bend it down slightly and readjust the chain.
Replace the flapper

Change the flapper

Unsnap the old flapper and take it with you to the store to find an exact replacement. In addition to the closest replacement, pick up a "universal" type.If you've completed the first three steps and your toilet keeps running, chances are you have a worn-out flapper. Turn off the water, remove the old flapper and take it to the store to find an exact replacement. (Hardware stores often carry a wide variety.) Most flappers snap over ears on the overflow tube. Others have a ring that slips over the tube.
Now here's the catch. You may not find an exact match. The range of flapper styles has mushroomed over the last 15 years, and you may find 15 to 20 flapper options on the store shelf. Some packages include specific brand and model information (so note yours before you leave home). Others have a "universal" label. If you can't find an exact replacement, try the closest one and pick up a universal type as well. They're cheap, and the extra one just might save you a second trip to the store! (Avoid the "adjustable" types unless you're replacing an adjustable one.)
Install the new flapper and make sure it opens and closes freely. Then test it. If the toilet keeps running or runs intermittently, you're not getting a good seal. Try a different flapper if the toilet won't stop running.
If you just can't find a flapper that seals, consider replacing the entire overflow tube/flapper. On most toilets (two-piece), this means removing the tank. It's not difficult and you don't need special tools. It'll take you about an hour, and you'll avoid that expensive plumber service call.
if you go to this link it will show you step by step on how to fix it. How to Stop Running Toilet Family Handyman

The level is determined by a floating device connected to the water valve. Some are on an angled arm and some move up and down.
Determine how your valve is shut off and either change the big round float or adjust the clips on the rising one.
Just keep the level below the overflow and the flush handle to avoid a running toilet or a leak.

There is an adjustment screw on top to adjust the float shutoff level. Models vary, but should be easy to find. It is usually where the float attaches to the valve body. Give it a turn, you want the float to go down. Flush and recheck water level and readjust if necessary.

Try adjusting the float level. The float is what tells the toilet to stop filling. If the float is set too high, then water will just go down the overflow tube and never be able to get to the level it needs to turn off.

If you can lift the float arm and it stops the water flow into the tank then the float arm needs to be adjusted. The proper adjustment will stop the water flow when the level is between 3/4" and 1" from the top of the overflow tube. The newer style valves have an adjustment screw that is easily located and can be adjusted without any dis-assembly.

My toilet is running, how do I fix it? To solve this problem, you'll want to ask the following questions:

1. Is water running into the overflow tube? If so, lower/adjust the float valve. By doing this it will float higher closing the inlet valve.
2. Is the chain too slack or too tight? Make sure the chain has only 1-2 beads of slack.
3. Has the water in the home or surrounding area been recently shut off for some reason? This could cause debris to come up through the water pipes and settle into the diaphragm seal of the fill valve. Flush out the diaphragm seal.

This is not an unusal problem; here is a video that may provide more assistance:

That is the cistern overflow running.You need to adjust the fill level in the cistern by adjusting the plastic screw on the ballfloat or adjust the height of the float if its the silent fill tpe

The screw can be used but only for minor adjustments. The missing tube should be replaced. If this doesn't solve the problem purchase a repair kit. The repair kit comes with everything you need for about $20 and can be installed yourself (saving $$$ if you called a plumber)

It's possible there's too much tension on the chain which won't allow the flapper to completely seal and let the tank fill. If this is not the case, the float may be stuck. If the float is sticking you're better off replacting it. If the tank is filling and water is overflowing into the tube, then it's the float.

The adjustment is inside. It just needs to be adjusted.