Moisture meters are notoriously inaccurate--so I would discount this part of the issue. If there is no delamination, water will not migrate far in end grain balsa. The problem is that the bolts and exhausts were not put in properly. If you breech the core, you must encapsulate that area--either relaminate solid glass, or remove the core around the opening and fill that with epoxy. Some folks use a drill with a short piece of coat hanger--die grinder or Dremel tool. I would find out if the core is saturated in other places also check all thru hull fittings. If the rest of the core is fine, and there is no blistering or delamination, then properly seal all hull holes and replace the fittings. If the hull is delaminated, or severe blistering then there is much more work to be done. I would advise against leaving the balsa which has been wet in place and just putting in penetrating epoxy. Dry out the area (heat gun, better yet vacuum pump with some heat) and see how far the intrusion extends--then properly seal the opening. Bob Austin