There are a gazillion threads on the 615 retracts and their issues. I installed them in a TF Corsair and spent a lot of time getting them to work smoothly but still found times they did not want to cycle crisply, usually when the plane was in the air resulting in a wheels up high grass landing. Got tired of it and followed the suggestion in one of the threads and cut a square piece of 1/4" thick aircraft ply to fit between the ribs where the retract rails were to go (the actual recommendation was a "U" but I thought a solid box would be even stronger), then cut an opening in the center for the retracts. This cured the cycling issue, the retracts worked every time. It may be a major project for you to make the modification but it is the only way to assure the retracts will come down and lock when you want to land. If you haven't already done so you should review some of the 615 threads and become familiar with the 615's short comings.