It's been a long time since I have messed with hydrovacs and I have 2 of them that need replacing and I'm not looking forward to it. Hydrovacs have 2 bleeder valves. If you have a maintenance manual, I guess you are aware of that. Every time I have had problems with a hydrovac, it turned to be air in the hydrovac. I have never taken a wheel off to get air out of a wheel cylinder. If you live in midland, there should be someone out there who has worked on hydrovacs before that could help you.