My 1983 O'Day 25 is now fairly watertype. There is just a small amount of dripping from the stuffing box which is normal. My various through-hulls do not leak, but they are old and I plan to replace them this year. I'll probably seal up a couple that are no longer used (disconnected knot-meter wheel; disconnected depthsounder transponder).
There was leakage at the chainplates before I bought the boat and while they had been sealed up, I resealed both of those points on the deck since you definitely don't want to compromise your bulkheads. I also had to remove rotted wood under the mast step and reseal that using the approach that Rich used on his 25 (lay in fiberglass resin so that any future leaks don't compromise the structural integrity of the deck). I fixed a few minor leaks at different points on the deck such as the rod connectors supporting the forward hatch. Finally, the bow ring was rotted out and the hose for draining the anchor locker had broken leaking rainwater directly into the boat. Once all those were fixed, she has been pretty dry. But with a 30 year old boat, you've got to be vigilant. By the way, I almost forgot to mention the 3 gallons of diesel fuel that leaked into the bilge a couple of years ago. Check those fuel hoses if you have a diesel.
Anyhow, I try to take them in stride when they occur, and track them down and fix them when they crop up.
Good luck,
Dave
s/v Lagniappe
O'Day 25