High Pressure function will NOT turn on

[ClassicsCW]

Woundering if somebody can help... In one of my self serve bays, my high pressure rinse will not turn on unless you change from another high pressure function (soap or wax). If it is in STOP or a low pressure function you cannot go directly to HP rinse. I switched out a metering box door and still not luck. I'm not sure if I have a motor starter going bad or how to check. It's older D&H GINSAN equipment.
Any advice is appreciated!
THx

 

[MEP001]

It's not likely to be the contactor, but if it's failing it might be having trouble pulling the contacts in. Turn it to rinse from off so it doesn't come on like it's been doing, then go inside and check the contactor to see if it's buzzing or if it kicks on when you rap on it lightly with the handle of a screwdriver.

If that doesn't do anything:

If there is a logic controller in the pumpstand electrical box, change that out or swap it with another bay and try it.