If this is wrong don't flame me, but I've got the same plane and I was recently advised to wrap the elevator cables round a perspex or acrylic disc with a hole through the middle(like making a woollen ball for the cat to play with) and then do as normal back to the RX. I've no idea why, and my planes barely halfway through the build so I can't comment, but it has worked on someone else's plane of similar design.