Like a lot of people I think the 90* tail control arm could be a bit more robust on the Blade 700X. Now I never had any issues in flight with the stock arm but it just seemed a bit flexible for my taste. What I did to fix this was take some two part epoxy and fill in the 90* corners inside the fork portion of the arm. The idea is to create a nice rounded curvature in each corner. Once dried the fork arms are easily 200% stronger and are significantly more rigid. This reduces any chance that one arm pops out of the slider. Cheap and easy fix!