I saw this thread soon after I ordered a 7950 and 7940 servo, so once it showed up I called HiTec and asked about the "issue" and I think they said the first run of 7940s made had one gear that was brass that was changed to steel. He said if it was new and bought from somewhere that wouldn't have it on a shelf for a year, I should have a newer one.

LOVE both servos by the way. Running LiPo and can't believe the performance!