I've had a Sieg X2 clone (Chester Conquest mill) for several years but until recently it's been used primarily as an accurate drill press. When I bought it I was aware that the plastic gears had a habit of stripping so I bought a belt drive conversion from Sterling Steele but never actually installed it as the plastic gears remained intact. I actually forgot I had it but rediscovered it when moving stuff into the new workshop so I thought I'd install it. No problems at all doing that but I realised that the belt – a Gates Truflex 0130 – was of the same vintage and I only had one so a breakage would mean mill downtime.
A quick search revealed that these belts are apparently impossible to source in the UK, which surprised me no end. US suppliers tend to impose exhorbitant shipping costs but I thought it would be worth while letting anyone who has this conversion know that I bought three belts (just to be on the safe side!) from Rockauto.com at a total cost of £13.74 including shipping. They came from the USA and took 12 days to arrive. Good service, excellent price, and I'm pleased to recommend them.