I've been using 6v packs for quite some time and in conjunction with Hitec servo's. Occasionally I'll see the jitters from a newly charged pack but after letting the plane sit a few with the switches on, it all settles down. Now if you had a marginal servo, this is definately the way to find it! Sorry for your loss. I believe in the KISS principal. Keep It Simple Stupid! The more you enter in the electrical equation, the more can go wrong. I try not to use matchboxes, regs, Y's, amp's (...etc) if at all possible. Use a 6v pack and burn in new servo's. They typically go bad within the first 10 hrs if they are defective.