Hydraulic assembly for staples chair Model : 24115D

The lift is pneumatic, not hydraulic. Replace it o replace the chair.

Google the chair model number. Or; go back to the store and take some pictures. of an assembled chair of the same make and model.

Your chair will not stay pumped up its due to the hydraulic pump thats in the chair all you have to do is find out the length of the hydraulic pump go online and Google hydraulic pump replacement and buy it from them

It could be faulty, but there is a arm under the seat that should allow you to adjust it, exercise that lever, perhaps the valve is stuck.

To lower the back, lift it until it stops firmly. Now let it fall all the way down. (It might need a little push to go all the way down.) To raise the back, lift it slowly until it clicks once. Each click is a height setting; it will stay at that height. Repeat until the back is high enough. To go back down, start over.
(This definitely applies to Tempur-Pedic TP4100 Office chair.)

Bolts commonly loosen up on these. You may be able to tighten them. I had to turn the chair over, pull out some of the staples that hold the material on and find the nut that went on the inside, then I was able to tighten the bolt again and staple the material back in place. I also had to make a new plastic cross bar for the scissor assembly by using a half inch PVC pipe and two flat plugs and two couplings, I then drilled a hole in the center for the screws to go in. Painted the newly made one with black plastic paint from Lowes and it's stronger now then before. If you want parts here is Home Meridian's contact..........

MAYBE DEPENDS ON WHAT TYPE OF BRAND IT HAS AND HOW FAR IT GOES IF NOT TRY A HOT GLUE GUN OR SUPER GLUE