Unfortunatley I've had the same problem with the new spur grear. I purchased the revised spur gear from Coasttocoastrc about 2 weeks ago.
I used it at one club race meeting and this is the end result. This is at the same track Drew races at.
I've used my Serpent centre diff with Serpent spur gear and it's been bullet proof for about 3 club weekends and a state title.
I think the main issue is the narowness of the Tekno spur and the flex of the chassis. The Serpent spur is wider and that seems to help imo.