Just a suggestion, not sure how your Monk is set up, but I thought my Marine Trader had a bad stern tube also. Turns out that the cutless housing flange on the rear of the keel was not sealed to the keel and allowed water to enter, where it worked it's way up outside the shaft log and satutated the area behind the buklkhead to which the forward cutless bearing was attached to. The sealant around the shaft log had eroded and allowed the water to work up to where it seeped into the bilge. This may not be the case with your Monk, but deserves some attention, since if by chance this is what you are experiencing, it's a whole lot easier and cheaper to repair. I have repaired this on my Trader so if you suspect that this may be the case, then I can tell you how I have repaired mine, which seems to have been successful since it has been 3 months since it was splashed and no leaks as of yet. Hope this helps, good luck!