fixed it i think, they guy in the shop told me how to do it and gave me the spur gear, but the method he told me didnt work, he said just remove the fuel tank and unscrew the nut and slide the gear off, but it didnt work I had to remove the engine, I noticed that red threadlock was used on the engine bolts, surely it should have been high temp blue, stupid hpi factory. I took it for a very short run of about 4 feet and it worked ok, just gonna leave it overnight for the threadlock to set.