Or he wrapped it out without a load on it. Either way, I wouldn't bother trying to fix it either. There are a ton of engines out there that will throw a 1/8th buggy around without much issue.
Personally, I'd avoid the dynamite ones with a spin/pull start, if you want to use the pull-start. They tend to break a lot.
I ran an LRP28 in my buggy when I had it. Way too much engine for a buggy, but it was fun anyway as a basher. Would have been useless on a track with the torque it had. There's an LRP21 that would probably work nice.
These are dynamite's that don't have spin start. Cheap, pretty reliable. Should get at least 6+ gallons of life out of them.
21:
https://www.rcplanet.com/dynamite-21-rtr-engine-with-ps-dyne0570_p/dyne0570.htm
28:
https://www.rcplanet.com/dynamite-28-rtr-engine-with-ps-dyne0571_p/dyne0571.htm
The 21 would probably get the job done, especially if your on a track. The 28 would have more torque for off road stuff.
Looks like LRP came out with a 28 spec 4. I had the spec 3 in mine:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGPZB&P=0