It has to be either blocked with something (line to and or from the solenoid), or no power at the solenoid itself. Take off the coil when the bay is on and see if you can feel the coil trying to "pull up" on the plunger. If you do, disconnect the output side of the solenoid and see if you get any flow. If you don't, there must be something blocking the
soap line somewhere. Trace back to the holding tank (
soap), disconnect the line from the tank. Make sure if there is a shutoff it is open. If you get flow from here, the kink / blockage is in the line to the pump. If you think it is just the solenoid itself, take the inlet side of the
soap line and connect it directly to the outlet side bypassing the solenoid. Again, if no
soap, check for a blockage. If you get
soap now, the solenoid is the issue. Something could be hanging up inside the solenoid itself. If all else fails, replace the solenoid with one you now works and toss out the bad one. It could also be in the switch out in the bay. Check the solenoid’s voltage and see if you are getting 24v ac at the solenoid. If not you’ve got an issue with a wiring problem. Trace all the wires, or better yet, switch a
door from a different bay and see if the problem follows or stays.