I have a pair of 645s that were in another plane up until a month ago... never once caused an issue.

I have now moved them over to a new plane. I replaced the gears in both of them before moving them over. Now one of them jitters at fulll deflection on both high and low rates randomly. There is no pattern to it at all. The other one has done this as well but I have only seen it happen twice while the other side of has done it about 20 times in the testing I have been doing the last 2 days.

What causes this problem? I am using a heavy duty 24" extension on them and being used with a Futaba 138 PCM receiver on 6V. Same receiver that was in the other plane.

I have tried switching extensions with little or no help.