On turtle deck, I did not cut side at correct angle. Had a narrow slit through flaperon control arm hole but after flperons installed and confirmed that hole cut-out on turtle deck side cleared control arm, I found I could NOT remove the whole turtle deck assembly. Therefore; I had to proceed with cutoff tool to remove 1/2" arc below the hole (as I should have marked and cut along to begin with) to allow deck removal. Oh well....one step forward and two steps back.