Self Bailers in a Winder
I've just bought MR3587, the self bailers seem to leak a bit.
There are a bunch of things that can go wrong with bailers so they leak, and quite a few of them are repairable, so I fear you need to spend some time with your head in the bottom of the boat examining things closely.
as a ribbed boat sailor, leaks are an everyday occurance!
A careful inspection as above and some judicious bending with an adjustable spanner cured the leaks on Heaven Sent. You are right, the bailers are vulnerable, usually the sides get bent slightly so the bailer doesn't quite close and then water leaks through the sides when down. The gaskets weren't the problem in my 20 year old boat and probably aren't in yours.
If you know the size and make of the bailer some of them you can get replacement seals, if can be a little fiddly but worthwhile, I have done this in the past. If you are local to Windsor area I would be happy to help out.