Les,
First, you need to know if the jack will go back up using the manual retract switch. If that does not work, you have a whole different problem. If the sensor/switch on the jack or jacks are bad, which I think is highly unlikely. This switch is a very heavy duty spring and gravity loaded switch. As the jack comes up the pad depresses the switch and makes contact. The rod is protected during driving and would not get dirt and grim as a general rule. The rod is only exposed while the jacks are down.
As Ed pointed out, when all four make contact, the all up light comes on and stops the buzzer. This all up light and buzzer are just for your information it is safe to drive. I believe it is part of the logic board as a simple relay function. Again, if it levels under auto mode and everything on the panel looks as it should after leveling is complete, Then your problem could just be the up solenoid for that jack is not working. If not, my guess is the control/logic board and BCS has a manual replacement system that work very well. BTW, I do not believer the jack up switch is available except in the used market.
Let us know, we are glad to help solve your problem.
Karl
