Bypass "Binary Pressure Switch" (Jumper it with CB-2 pulled as this is a hot circuit).
The coil in "Motor Power Relay" might be going bad (Opening when hot - closing when cold).
I would think the second is probably more correct. Pull CB-1 and put a meter across the power contacts of relay. See if it opens and closes continuously. That diode shown below the power relay is a
Suppression Diode
, it could be breaking down also. Most are built into the relay itself.... if not, one side of it can be disconnected for testing purposes.
You said "Auto" position. I see no "auto" on your print.