Whats up guys,

I've been running my ERBE now on 4s ever since I've received it a few months back. A couple times I've used a pair of 3s 5000mah 65-130C Lipos and all was well and fine. Well the other day I was showing a buddy the 6s speed and all and later on that day when I got home, I ran it down the driveway and back and it started making that deadly "I need a spur gear sound". I swapped it out with another one I had and after about 30 mins of running, the spur gear went out in that one as well. I'm not doing anything ridiculous either. I was still running the 6s, but was just running through the yard occasionally and hitting a ramp I built a while back a few times. Nothing over dramatic. I changed that one and spent 15 mins making sure I had the best mesh I could get and broke that one too. I made a quick run to the hobby shop and bought 2 more just in case. Needless to say, I am on my last one. I know you can run 6s on a plastic spur and I know how to set mesh, or at least I think I do. I had absolutely no problems until I bumped up to 6s. I don't have any photos of the spur gears off hand since I'm at work. Is there something I should be looking for that might be broke or causing this issue outside of proper mesh? The gear looks like the pinion is just catching the edge of it. Could something in the chassis be flexing and causing the motor to pull away from the spur enough to grind it off? Any and all help would be greatly appreciated. TIA