Our 926M needs a new lower cushion as 1 side (left hand side, from getting in and out of the machine all the time) the whole cloth and the foam part is hanging down. Asked my CAT dealer parts guy for a replacement part and he jokingly asked if i was sitting down ;-) Cat wants 1250€ for it. i told him i only wanted the cshion, not the whole seat Is there somewhere i can get a cheaper, aftermarket option?
If you can live with the machine being down for a few days, try one of your local upholstery companies. Surely there must be a few places around your way that do that type of work. The key would be in selecting the correct foam and a suitable hard-wearing cloth for the covering. Other than that any upholsterer should have all the tooling necessary to do the job.
As long as the seat base isn't all rusted a good upholstery shop could repair it. The other option is a complete new aftermarket seat. I think Ultra Seats ships all over the world and are more reasonably priced than other brands.