The Futaba 3004 is a good servo. I'm also assuming it's a NEW servo. If it's a used servo, you might have a dying peice of equipment.

I saw a problem like this last weekend. In this case, the servo was just rotating so far that it was getting near to binding the internals. A little "dial back" and it did fine w/ no more funky sounds.

The LONG SHOT chance is that you MIGHT have gotten a bad servo from the mfg. I'm an Industrial Manufacturing Engineer and I can tell you that SOMETIMES even in the best plants, with the best staff, that a sub-par item slips through the "quality net"..... If your throws aren't stretching it too far (or better yet, when it's COMPLETELY UNHOOKED) and it's still making these noises at the far ranges, I'd talk to the seller and get another new servo to replace it. Just as a "test" unhook another servo of the same type and put it in that postion to see if IT makes the same sounds (just a thought....)

WAY better to be safe than WAY sorry!!!!