The handle gets loose and we have to open the tank and tighten the black circle that is connected to the handle. The black circle keeps getting loose even after one flush

is there a lock nut on it? take the tank lid off and use both hands to tighten turning the pieces the opposite way from the other until its tight, sometimes if you tighten too much the handle doesnt work all i can say is you might have the wrong handle nut on it

follow this steps and fix it.
Adjust or replace a flush handle:

1. Remove the cover from the toilet tank (the higher part at the back of the toilet). If the handle is loose, tighten the locknut with a wrench. If the nut won't budge, apply penetrating oil and let it set before removing.
2. Unhook the chain from the trip lever and slide the trip lever, with the handle attached, through the hole in the tank.
3. Soak the handle threads in vinegar for an hour or so to remove mineral deposits, then scrub clean with an old toothbrush.
4. Reinstall the assembly, tighten the locknut and adjust the lift chain (see below).

Adjust the lift chain:

1. If the handle must be held down while the toilet is flushing, the chain may be too long. Shorten it by hooking the upper end through a different trip lever, or use long-nose pliers to open and remove some chain links. Alternately, replace the chain with a new one.
2. Some flush assemblies have a lift wire instead of a chain. If the wire binds against its guide, flushing is impaired. Loosen the guide with a screwdriver, then adjust it so that the flush valve falls freely onto its seat.

dalbritton-

The handles are fixed to the tank body with a hex nut on the back (inside of the tank. They may not have been tightened properly from the factory. Tighten a bit with a wrench and you're good to go!

Regards,

DIYpro

should be a small access cover on the handle top and bottom pop them open with a flat small screw driver screws should be underneath

To tighten the screws on the handle, you have to take the top off. To do this, you have to take the black top piece off, and then you can reach the screw that holds the aluminum top. To remove the black top, use a small screwdriver to push the tabs that hold the top on. You can reach these tabs by opening the lid about half way, and going through a hole that is created by the hinge.

If it is a Delta, there is an allen screw on the underside of the handle. If it another brand, there is a cap in the center of the handle that you can pry off and tighten. If the cartridge is loose and leaking, tighten the packing nut with a channel lock wrench.

Ok you need to use plastic or rubber washers against the glass so it doesn't break. To stop the handle comming loose again you need to put "Lock Tight" on the screw threads then tighten carefully only untill the handle isn't loose. You can get this from any good hardware store. cheers

Please give feedback

heyii if you can easily remove the seat then do it on your own or take your bike to the nearest mechanic and get your seat opened.. the end of tank is covered through seat and when the seat is opened you will be able to see a bolt(or may be two) and you can tighten them up. but also there is a little play provided by the manufacturing plant to resist shocks..,so keep this in mind while tightening the bolts.. Belated Merry X-mas and Happy New Year [:)]

Hi,
You may have to get some loctite brand paste in a tube for applying to the threads of the bolts that hold it on.
This will prevent the screws from loosening.
Another way would be to get some spring washers or star washers at your local hardware store such as menards.

I would try putting some locktite on the threads so It wont come losse anymore.