Hi,
I'm new to this site but just wanted to share my experience with the brush-roller drive belt.
We have a U91-MA-B MACH AIR. A very light weight machine and very effective cleaner.
I tried to find the brush roller drive belt on various Vax and espares web pages, not successful at all.
Contacted VAX and was told that the belt is not a serviceable part (what a load of garbage) took the machine apart got the number off the belt and googled it. Straight away the very part popped up with a reference to being a VAX part. Bought it, fitted it and its working great.