jr high volt woes

[SDS Customz]

Me and a couple of other guys have purchased the JR high volt servoes. they are rated 480 @7.4 volts. ive been running mine on a berg crawler and the things (both of the ones that I have purchased) eat the primary gear(plastic) @7.2 volts generally within 8-10 batteries of run time this kinda concerns me being these are 200.00 servoes and i'm not running them wide open. the end points are set up properly (servo never hums at the end of the stroke) Anyone have any suggestions. Ive always ran Hitechs @7.2 volts 430 inch oz and never broke a gear. while I love the extra power in the servo im not sure if they are worth the head ache