Why did I replace the roter? Good question. It was my fault. I was not careful enough fitting the perfectly good stator after replacing my sprag clutch. (The sprag job worked out perfectly and only cost $100) But I forgot about adjusting the position of the stator and just bolted it on. After a short ride I noticed it was not charging and a bad burning smell. Took the cover off to be greeted by chewed up roter and stator. I now know how to get that gap right and find the best method is to wrap a plastic strip from the bottom of a $1.00 shopping bag round the roter, slip the stator on and tighten the three nuts carefully, checking the plastic has even tension all round. If not, a slight tap with a hammer in the right direction and then remove the plastic. The gap on mine is perfectly even and I guess about .45mm as that is the thickness of the plastic. But if you say .009, if you mean inches, that converts to .22mm so my gap is too big by a smidgeon but there is no way to adjust it. What do you think?