I recently helped a friend out, his diverter valve (American Standard, low end seperate hot and cold) was leaking out from the valve itself. So when, I opened it up it was quite worn and my suggestion was to just by a new cartridge. I installed the new cartridge and everything was fine at first, but the problem is now (which got progressively worse) when the valve is closed so that the water is diverted to the tub, the shower gets some supply and visa-versa. I had not opened the new cartridge, but it didn't have any packing when I finally looked at it. I think, but am not sure that when I installed it I may have overtightened it to seal it from leaking out of the valve itself and in the process may have deformed the brass washers. Was the cartridge supposed to come with packing? Anyhow, I think we have to get a new cartridge and this time put packing in it and my question is, how do I gauge the proper amount of packing to use?