Unfortunatly you don't have a trex or their design of tail so if they lube their belt they still have that idler to hold tension on the belt which runs on a much larger pully (less bend on one sideand more tension on the belt). The King doesnt come that way and only has that tiny cog pulley to collect gunk in and fill the cogs, dirty belt from lube and slipping is common on Kings. Due to tiny stock boom you cannot install a larger pulley and even if the boom was larger and you could you are still limited by the size of your main belt pulley as far as getting up tail speed for tail control. That is why there is a 43t conversion for the main pulley.
It is common to ground the boom to the - battery with the cf boom on a Trex when they couldnt locate the source of static vibration or correct it any other way. the Trex 500 seems to be very prone to static and it has a metal boom.
I usually bench test and try to duplicate the problem. Also if you have a way to tie it down do it outside so you do not have interferenc from say flourescent lights etc.