Problem with a 1977 ratgo rascal compactor/vibrator

:BangheadI have a 1977 raygo rascal 320a and after setting for about a year and now it wont vibrate, I took the solenoid valves apart and they look free and clean, this system looks really old, why two pumps? Before it all ways worked great and the solenoid on the left side has wires to it and the solenoid on the right never had any wires hook up and it worked fine with the switch. anyone work on these much ? thanks