Running out of ideas... probably wouldn't hurt to experiment with a different brand of servo.

I recently started testing the Team Powers Servos in my 1/10 cars and they have been doing very well for me

Biggest selling point for me are gear sets are only $13 making them one of the most affordable servos to maintain over the long haul, though I was only recommended these servos by another sponsored driver in my area, I only have a handful of race days on them so far no complaints!