BOUGHT a GMS 76 and it vibrated like mad. I was ready to throw it in the trash but instead took it apart and found the crank counter weight ran full circle although thinner on the crak pin side.I ground away all of the thin part and even rouned the crank behind the pin.Hoever, don't get carried away here or you'll weaken the crank.Put it back together with a new ring and now it is one of my favorite engines.Try it you'll like it.