I just removed my shower valve cartridge assembly to clean (we had low water flow), the left side input screen (it was clogged with scale particles). I reinstalled the white plastic screen retainer (one one either side of the valve mechanism). I dabbed a little silicon grease on the o-rings and reinstalled the four screws. Turned the water back on to the house and got a cup of coffee. When I returned to the bathroom, water was dripping out of the hand held shower (shower fixture only--no tub). Turned off main again and removed the cartridge assembly thinking an o-ring pinched/split/fell off. Both were on the unit and the small dab of grease was smeared. The valve assembly has be in use for 9-years without a problem and this was the first time I've removed it since it was installed. Should I install new o-rings or could the valve assembly be my first step? Thanks... A few more items pertaining to this trouble. I removed the mechanical stop on the splined shaft to verify the handle was completely closing and it appears it is, there's no sloppyness at the full on or full of stop. Greased the splines and reinstalled the stop. Put the outer sleeve assy back on and turned the water back on. There is a significant drip still andwhen pulling the whole valve assy and putiing it back in there doesn't appear to be any slop, so I assume the o-rings are sealing. Additionally, I did not see any debris in the inlet side of the black valve cartridge and the outlet side springs open and closed with no sticking (small little white plastic pop valve).