Beambox Pro belt tearing after rising on the idler pulley

I have noticed my x-axis belt that moves the tool head from side to side has begun to tear and split after the belt began rising up the idler pulley during jobs. I am looking for a replacement but cannot seem to find an ‘official’ FLUX Beambox Pro belt on any of the retailers or from FLUX’s store.

I’m sure I can find a replacement online but I was wondering if anyone can help me with finding a quality belt that is also the correct size? Any advice would be great thanks.