Could use your advice. Have a 15 yr old Delta 3 handle shower faucet. Over the years have been successful replacing the cup and springs. This time replaced the cup/spring, leaking worse than with old cup. So I bought a new stem,cup and spring, same results.

Water dripping out is cold not warm or hot. Inspected inside (cold side)valving cup area is clean, little lime below outside the cup area. Not seeing or feeling any burrs. Handle turns nicely, no hang up. Guess it could be the hot side but that's leaked before and
the drips are warm.

I'm no plumber ;^)

Before you replaced the cups did you turn the water back on to flush any trash out of the open valve body? Sounds like you may have some dirt or trash in there. Good luck, Tom

Appreciate the reply. I flushed both hot and cold sides out. Had assumed the hot was fine, but no. Even had to
Scrape (carefully) inside the hot side to get back to brass. Guessing lime deposits. Old stems looked good, new
Cup/springs and buttoned back up. No drip. Thank you for the pointer!