BV told me that they (BVM) had attached a weight to a 3421 and put it on a servociser and let it operate for several days with no problems. His conclusion was that the 3421 with the gyro and in some cases with an unregulated 6 volt pack were frying. I still have 4 of them and plan to use them in a quickee 500 plane whenever I get around to building it. I think they are good servos as well but I don't think they are up to the task with a gyro set on ANY gain.

DR