I misread the itemized bill. I should have written "air bleeds".
My handyman came back and said pretty much the same thing that you just said. The pressure release valves have gotten old. It releases excess pressure, but it doesn't fall back in its place properly, which is what causes the continuous leakage. This second repair will cost us an additional $250. We have paid $650 already ($120 for just walking in the door and adjusting the pressure and $520 for replacing the tank, make-up valves, and air bleeds).
Are his prices normal? Was the initial repair necessary?
Thank you! Everyone has been so helpful!