Rear Brakes will not engage

[zubzub]

Do you have the shop manual for your bus?

[miles2go]

Got a Maintenance Manual in my hands. The mystery component is a check valve. The plug works fine where I put it. I have rear brakes that work as they should now. So it was not a recent problem as I thought. I had only been using front brakes all this time. I always thought the brakes were kind of weak. Have new front shoes and the drums turned. Have new rear shoes but did not turn drums as they are at their limit, front drums had lots of meat.

She sure stops a lot better now.
Thank you to everyone for your advice and guidance.

Andrew.