with this kit, almost everything was designed a bit oversized and you would glue the pieces in, then trim them off. This is ok but isn't precise - LOTS of fabrication.
On the retractable gear mounts, I had to fabricate a couple of new ribs. It was amazing that right out of the factory, the right and left halves were not even close to the same! Oh well, that is what happened before computers and precision lazer cutters. If anyone is building one of these, the directions and the plans say where to glue in the mounting blocks on the ribs for the retracts I suggest that you glue them maybe a 1/16" deeper than suggested so that the gear mount plate will be below the skin of the wing when finished.
The front of that rib doesn't look very nice and I took a dremel with a sanding drum and made it look better before installing it in the wing. A 5/8" dowel cut to length goes there and against the front of the inside of the leading edge of the wing. Make sure to double check the fit before glueing it in!
http://www.youtube.com/watch?v=WakievP8VPc
there are several videos on this and more.
when I downloaded thes videos, I didn't really edit them because there was so much and it would have taken forever to do so. As a result, I just uploaded them in order, raw. So, if it gets boring, just fast forward them.