Bissell PowerSteamer ProHeat Carpet Cleaner Service Repair Guide
This official Bissell service guide dates from 2004, and although is for an American machine, the UK did get this machine as the ProHeat, and many of the pages will still be relevant. If you are actually trying to repair one of these things, I do have the below as a searchable PDF so let me know if you want a copy of that for ease!