I have an update on the retract installation. Shimming was not a good idea. I put the wing halfs together and noticed [because of the shims] that the wheels were not at all 90 degrees to the floor. This didn't work so I wanted to remove the shims. I decided to investigate and opened up the retract. I found some burrs where one of the screw heads apparently protruded to the inside of the housing and prevented the retract to close all the way. It was way in the corner of the housing. I removed it and also cut a chamfer to the edge of the plastic part of the strut ( for lack of a better word) and now the retracts will close all the way and no shims are needed. This was found on both retracts. I know this is an old thread but I thought I'd post it anyway, someone might need the info in the future.