Built stock, the Sig Cap wing has short legnths of dowel glued only into the lite ply at the front of the wing. I have built 2 of these and in both cases, after a few flights the dowels got loose and wiggly. Another one at the field had the same problem.
The fix is to get 5/16" dowel and cut pieces long enough to extend back to the ply joiner. I cut out some squares of 1/4" ply, drilled in the center for the dowel, and glued the dowels into the ply and the ply onto the forward face of the wing joiner. You have to cut out 2 small access holes in the top of the wing to do this. It's easy and once patched, doesnt show since the patched area is inside the wing saddle. I also reinforced the dowel holes in the fuse, gluing predrilled plywood squares on the forward side of the former. Again, it is easier to do by cutting out the ultracote from the front of the fuse. This area is easily patched and covered by the cowl. I dont think this is your problem now, just a heads up to a potential problem.

Peter