ive never even seen this early version of this mechanism and ive had more than a few 500s,its a fickle thing thats why it was upgraded/modified in the 500s then reworked totally on the 550s,i wouldnt persist with fixing that earlier type?id try and find a later unit or 550 unit,youll be a lot happier with the out come,ive busted a couple of improved 500 transmissions and found the 550s to be some much better and smoother all over,mind you i aint been easy on them,the 550 is a stronger transmission and clutch full stop.