Tony,

have you seen this?
https://www.model-engineer.co.uk/forums/postings.asp?th=143379

It might be worth contacting Adam to see how he went with his belt change

Your “selector shaft arrangement” – do you mean the shaft and bearing that enables the epicyclic gears? Mine only had the inner race on the shaft when I got it.

Hi Tony

I've got a new bearing for these sitting in my toolbox, I used to work where we had quite a few of these and I used to look after the maintenance of them, if you PM me I'll post it to you.

Quite easy to remove the spindle for belt change, but never dismantle the epicyclic back gear unless you have to, horrible fiddly job to put back together, our very upright foreman fitter used words I never knew he knew whilst grappling with one.

Dave

The inner race on mine was reasonably easy to slide off the spindle – a slight friction fit. The bearing really cannot go anywhere once the spindle has been locked.