I have an older Delta tub and shower valve I believe its a 1400 series n/s it has the brass nut that holds the handle on then it has the temp cont valve not too good with valves. I have changed the springs and cups and the seal that goes around them looks like an 8 and it is still slowly leakin by. I'm just wonderin if I should replace the whole thing or just the cartridge and if it be the cart which cart would it be
There is a plastic adjusting ring with two opposite slots inside the middle of the domed cap under the handle. Turn it clockwise with a Delta tool that comes with most Delta repair kits, or use the tips of a pair of needle-nosed pliers to turn the ring to tighten it up. If the threaded ring and the cap threads are corroded or clogged with minerals, spritz a little WD-40 on it to loosen it up.
Do not over-tighten the adjusting ring as that will make the faucet hard to operate and wear out the internal parts faster.
Just adjust it snuggly to where it will stop leaking. You do not have to turn the water off.
If you are talking about the one with the plastice cartridge inside you can just replace the cartridge if you are having trouble making the new seats and springs work for you. here are a couple of different cartridges. which is the one you have?