dps wrote "........Not sure who b&q is, but you might look at Home Depot
or some building supply place for tracks/wheels for sliding doors
..............."

B & Q are a british firm similar to Home Depot.
I would ask at B&Q if they can get spares, or for a contact to the makers.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk