I've got a leaky bathroom sink with a Delta 2-handle faucet that I'm unable to permanently fix. Every time I replace the seats and springs, the problem goes away for a day or two, but then returns. Every time I pull out the cartridges to replace the seats, I find the old seats are nicked at the top (see photo).
I've gone through this routine five times in the past few weeks, so I'm presumably doing something that's causing the seat to be damaged after some use. Anyone have any idea why?