There are a couple of ways to fix this. First is to just tack glue the parts down. You don't need to use a lot of glue at all. I just place a drop where I need to hold the part and hit it with kicker. When I am ready to take the parts off the table I either use a razor blade to get under the part, or squirt just a bit of acetone where the part is glued to the table.
If the only thing breaking off is the jig tab on the rib, don't worry about it. If you build the wing all the way till it is done on one side, you don't need the jig tab anyway.
Hope that helps.
Hans