red dust on the engine pulley seen at 3:27 is iron oxide, clear sign of spline wear (the product of fretting wear). also the retaining nut moved inside the locking washer meaning the shaft/pulley has considerable play. if caught early, the shaft splines may be still intact but the wear progresses fast as the 'red dust' is super abrasive. edit: 4:58, right side of the screen, the splines of the counter-shaft present substantial wear :(, i hope it was replaced. special grease is required on the splines, 60% moly to impede fretting wear.
