Thank you John!

It has plenty of oil, though I am going to change the oil to just to make sure it has yellow-metal safe oil in it.

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It is worth double checking that the primary chain isn't too tight, these gearboxes are renowned for not tightening up properly on the frame and can easily crack when done up too tight. When we were in France one year a Dutch lad on an M21 broke down as he couldn't change gear. We had been on a ride out and it was slowly getting worse until the gear lever was too stiff to move. After lots of waiting around and taking gearbox casings off etc, it was found that the primary chain was too tight and seemed to have got worse over the day. When it was slackened off, the gearbox worked perfectly. Just a thought

Gents,

A bit late due to holidays but:
Do not forget to mention the possibility of a loosening clutch centre nut!
These tend to come loose sometimes leading to difficulty in changeing gears.

Cheers,

Rob

Did Timothy sort out his gearbox?
I only ask because my change was getting progressively worse. I had bleak thoughts. It turned out to be a loose nut on the rocker shaft in the doll's head. Now the change is very good.