The Losi is notorious for burning up throttle servos. Everything must be perfect or it'll eat up servos. Losi has a "throttle addendum" and a radio tray addendum. Follow it word for word.

http://www.losi.com/Products/Support...rodId=LOSA0802

The chassis flex is what causes the servos to blow. Under flex, the throttle linkage binds, in turn, binding up the servo. I don't install the screw that holds the battery box part of the tray to the chassis. This allows the chassis to flex without flexing the radio tray. To keep the battery box from bouncing around, you can use velcro to fasten it to the chassis.