Hi RK,
I was also having a problem with an inner hull leak on my Widgeon. What I ended up doing was actually filling the inner hull with water via a hose to the inner hull drain plug to try to discover exactly where the problem was coming from. To my surprise there was about a straw sized stream of water that began shooting from the centerboard bolt hole! The two hulls are exposed there and after thirty + years of pulling that bolt in and out, the seal was broken. I swear on a stack of pinochle cards that after a half hour (or less) epoxy repair to the seam and a little sanding to make sure the bolt went in and out nicely, I never had any water in the inner hull again.... and what a difference that makes in the handling too!
Hairline stress cracks around the the centerboard was a minor secondary issue on my boat that wasn't an issue at all once the leak into the hull was corrected. Also had a bit of weeping around the CB bolt itself. A little silicone sealant between the bolt and the gasket before putting the bolt in at the beginning of the season solved this problem.
BTW, Between the two hulls all you have is a foam core, no wood or anything else. The fiberglass does all the work. Hope this helps. Widgeons are great little boats to work on and their beauty is in their simplicity. I read of one guy who filled his whole inner hull with epoxy to solve a leak problem. Yikes, that must have cost a few pennies! ..... and added a few extra Lbs too %^O