I have a 67’-69’ pc50, with a 4 cycle 49cc Eng. Can someone tell me how this crankshaft works when u switch from free wheel peddling to engage to start Eng.? One day I came out to ride and I rolled it outside, flipped the lever to pedal it to start and it’s locked up? I flip the lever and peddles rotate both ways freely. Flip the lever to start and it doesn’t budge, and the tire skids across pavement?? I tore the Eng apart and found nothing broken, no shaving’s, no teeth broken off.? The absolute only thing I can’t figure out is how the crankshaft engages and disengages? Could it be my problem? I can’t find any videos or anything telling me how this piece works. Plz any advice is greatly appreciated!! Text me 678-722-1262