Since you are switching from service to run position I am assuming the unit will not start in the run mode.
Set service run switch to run. Sit in seat and check that the instrument panel lights up. If not check the 5 amp fuse in the engine compartment fuse panel. It is the 2nd from the bottom on the right fuse bank. If the fuse is good the seat switch or seat harness may be bad.
If the lights come on momentarily and go back out you should still have two lights lit, the parking brake and seat belt switch. Connect the seat belt and the seat belt light should go out. If not you are either not getting power from the seat switch or the seat belt switch is bad. When the seat belt is fastened you should have 12V on each terminal in the seat belt connector.
The reason your bucket is working is probably because the pin in the solenoid is stuck up and not engaging the control valve spool. You should have this repaired.