How to unscrew lid on 3 gallon tank sprayer roundup

No 'replaceable ' parts. buy a new one, and do not junk the old one, use it for spares.

The pump is a twist to unlock. Most likely you left it for a while tight screwed on. Push the handle all the way in.. Put a stick in the handle, then slowly unscrew it. This will give you more leverage.

Howdy MMis971,The sprayer just needs to be pushed down by the handle as you turn counter clockwise. This can be made a little easier by unscrewing the nozzle where it connects to the tank to release any pressure built up by pumping.
Happy Gardening,Coach Dave

type roundup spare parts into your search box then brose the list that comes up

Howdy g5483,Most reputable retailers' will either let you exchange the sprayer or get you the part. At The Home Depot we will gladly do either one to get you what you need.
Coach Dave

Check under the lid/cover for a rubber gasket. This may have gotten unseated when putting the sprayer top on. It must form a tight seal around the lip of the sprayer top in order to keep the pressure. Alternative: Put water in the sprayer leaving some air on top to build pressure. Put a few drops of dish soap inside and gently stir. Put the cover on, and tilt the sprayer to coat all areas at the top. Start pumping and see where the bubbles come out---there is your leak. If it is near where the sprayer hose enters, and it is a permanent mount, you may have a bad seal. If the sprayer hose unscrews, you may need a new rubber washer inside. If bubbles come out of the wand, or other plastic seams, you may have a crack in the plastic. Depending on the location, you could epoxy over the crack to seal it permanently. Good luck.

it should tell you on the induvidual bottles/cans of weed/grass what proportions of liquid/water to use.

Hello,
Yes I do use it, you can put about 1qt of round up for every gallon of water. This should kill your weeds, for most precise mixing instructions check the bottle label.
Thanks.

6 oz per gallon of water for weeds and lawns

The handle pushes down and locks to be carry or to unscrew it. Push handle down, then twist left to unscrew. It may take a bunch of force to start. Better to hold the sprayer down and relieve all pressure before doing the unscrew.