Most of the searunners I've looked at have needed (or already had completed) some repairs
to the decks or around some of the many hatches. Fortunately on a plywood boat
are very straightforward if not too extensive. These problems can be much, much worse on the polyester (vs epoxy) boats.
But remember on these type of repairs what you see from the surface often gets 10 times worse once you start to dig into it..
Overall needing winches and having been sailed for a few year with a blown motor
sounds like a bad case of deferred maintenance
(you know they didn't put $ into it if they didn't fix these things) that will show up elsewhere,...but it apparently still sails
& still could be a fair deal if the bones are solid!
For the right person, pretty simple to grease & rebuild
or replace (perhaps with used) the diesel
, or even throw on an outboard
Another thing to check for on a boat
like this would be waterlogged boards or mini keel
. The centerboard
if free of obstruction can be pulled up through the trunk while the boat is in the water
using the main halyard