David P wrote:

Mum lost her balance in the shower and has succeeded in breaking the
sliding door gear at the top of one of the (corner opening) sliding doors.

I can find no brand name anywhere on the cubicle or doors and suspect it
was the original builders supply when first installed c16 years ago.

The wheel itself is grooved as though it should run *on* a track but it
actually appears to be running in a c-shaped track.

Wheel diameter is c16mm diam.

Can anyone suggest any uk vendors of 'spares' who may be able to assist?

There are loads of different types of shower roller, as I've found to my
cost before.
Make sure you get the correct size, and profile of the roller.
I've used these recently, with no problems:
http://showerpart.co.uk

(I'm glad you brought this up, I have to order a new shower door handle
for a customer, and they sell those too)

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