I read through this one prior post on same subject: http://www.houserepairtalk.com/f33/toilet-tank-leaking-into-bowl-1332/ Replacing the flap (which seems to seat fully) did not solve the problem, so maybe I should replace the entire Fluidmaster apparatus. I'll purchase it to have it available for the plumber before I make the appointment. What I'm wondering is could the slow leak be caused by a problem with the toilet tank itself (and not the innards)? I don't see any hairline cracks. Since I turned off the water supply, tank water is only about half inch in the tank bottom. Should I put food color in the tank to see if it goes into the bowl, since the water's not high enough to reach the flapper? I'm trying to rule out the need to replace the tank or even the whole toilet (Almond American Standard Cadet circa 1999). What I'm asking is if there's any reason - other than the flush apparatus - for the tank to be leaking into the bowl? My resources are very limited, and I'm trying to keep the plumber labor to a minimum so I don't want any shopping time or return trips. That's why I've already acquired the Kohler faucet kits to repair the kitchen and lavatory faucets - to have them ready for the plumber. The dis-attached bathtub drain stopper also needs to be re-attached so it works with the toggle handle. Hopefully, I'll be able to get it all done within the $199 voucher from Angie's List.