I have a Mountfield Mercury 16. Model 420 SP. Year 1997. I have dismantled the rotor for cleaning and maintenance, but not sure how many key pieces are required. There is a slot for a straight bar type, and on the opposite side of the drive shaft there is a space for two crescent shaped segments. I only have one of the latter type. Is this sufficient and what is the design requirement ?
Simply re-fit they key that came off it when you stripped it. The engine is designed to fit a multitude of applications- hence the different keyways. You don't have any missing- it only has the one.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lawn mowers.