Posted before but now have a new problem- my husband got his bike running and idling good finally but then it made a grinding sound that he described like something got stuck in some gears. So he turned the crank shaft while I was recording inside the valves and one of them wasn't opening at all. He was thinking it's a possibility when his buddy was helping him he could have knocked something in it, that's why we were checking out the valves. Doesn't know for sure though. Any ideas on why or how to fix it?? Thanks!