Roger, Yes!!! The hinges must not be used. I saw failure on the elevator and now use 4 DuBro hinges per side. Gotta be careful as this is an engine thread not a corsair thread but dang it what a perfect combo. I flew my Robin Hood 99 with my 9-90 the other day. I did the full regime oiling the engine after the flying for that day. The next day the engine felt lightly "crunchy" so I removed a top and and bottom cam follower and flushed with more after run oil and evidence of water was present!!! Now it is clear and smooth. Moral of story; check you engine the next day for smoothness, if not hit it with more after run to get that evil corrosive and water out. Watch out for hydralic lock though with all that oil. Seems more of an issue with the 9-99. Worth the trouble as the engine was flown 8 times for around 10-15 min each for a great day. -Tom