I've got a similar problem. My showerhead started dripping slowly but before long was up to a drip every couple of seconds. I tightened up the three cartridge screws to start with, which took to a drop every 5 seconds. Then I replaced the valve cartridge (American Standard 023529-0070A) and it slowed down to a drop every 10 seconds. After reading the posts above, I got a small tub of Oatey silicone grease, put it around the three 'rings', and it dropped slightly to a drop about every 12 seconds. I removed the three PBU screws and tried to wiggle it free while I had the cartridge out, but no luck. It's pretty firmly stuck, and I was afraid I'd crack if I put too much pressure on it in trying to loosen it. I ordered the matching PBU to the new cartridge and it should be here in 5-6 days. so my question is, now that I've got the leak as slowed down as far as it is, is it likely that the PBU is responsible for such a slow leak? I was thinking after reading the boards that a PBU leak would usually lose it faster than 5 drops a minute. If you think that's the correct next step, once the new PBU has arrived (I've learned not to do something like this without have the replacement in hand), what tips can you share as to best loosen it while doing the least amount of damage? I'm concerned about possible collateral damage to the base where the PBU mounts to.