I'm glad you hear the 5 small clicks coming from the accelerator box under the driver's seat. In that silver box ( attached to the frame) is a micro-switch for each solenoid.... and there is a micro or 2 on the F&R that switches the negative current to the solenoid activation circuit... it was a good system for it's time. Remember the solenoid closest to the driver's side is the master... it switches the power supply to the other speed solenoids...... it seems complicated but it is not once you see how it works, it is just 1980s technology..... I have new solenoids if you need. But you need to check the micros first and make sure they are working ... continuity test their switching beginning with the F&R micros. Avoid taking the accelerator box apart if possible... it is a can of worms
Are all of the solenoids clicking now? Test this with the rear wheels up off the floor! Each solenoid click should result in an audible & visual increase in rear wheel speed....