Haven't been able to locate a donor machine or get a replacement pulley so took a last ditch look at it today.
There is a bolt that holds the pulley on and screws into the end of the cutter blades and it appeared that the bolt had somehow come loose and the pulley spun on it and being softer alloy damaged the flats and rounded them off.
Today it was kill or cure so took the pulley off and got into it with some tools and made flats again enough for the bolt to sit correctly.
Fired the machine up and it was a bit noisy in drive but was working, so cut the lawn then right at the end I put it into neutral to empty the catcher and the belt burned and smoked up.
Took the casing off and the bolt for the pulley had unscrewed itself again which is strange because the thread is opposite hand to rotation.
I didnt use loctite, but I doubt that would help.
The bolt was rock tight when I tightened it because I have a special tool I made 20 years ago with 2 pins that fit the holes on the pulley and blocked off the blades from turning with a piece of wood and tightened the pulley bolt that way.
Anyone any ideas as its puzzling me how a bolt can unscrew itself when its opposite hand to rotation
