not sure on what side the hopper switch is on the cast model, but on the steel one i have, it is on the front right corner. you should be able to follow the position and figure out what wires correspond to it.
try this first.
other reason that could cause the auger not to turn (from the technical manual):
http://www.enviro.com/images/manuals-brochures/owners-manuals/C-12003 Instruction M55CFS Domestic Technical Manual.pdf
5. Unit is on but auger motor does not turn at all.
• Check the line fuse to see if it has blown.
• Check the Door and Ash Pan door - THEY MUST BE CLOSED TIGHT.
• If the Auger gear box does not turn but the motor’s armature does try to spin, then the auger is
jammed. Try to break apart jam by poking at the jam through the drop tube. If this fails then empty
the hopper and remove the Auger Cover **Remember to re-seal the cover after installation**
• Auger stopped running. Pinch, break or blockage in Vacuum Hose - Check hose for pinch points or
damage, replace or re-route as required. Blow out Vacuum Hose and intake pipe.
• Damage to wires between Circuit Board and Vacuum Switch and Auger Motor - Inspect wires and
connectors.
• Vacuum Switch failure - Bypass the vacuum switch, if this corrects the problem check for above
problems before replacing the Vacuum Switch.
• Blocked exhaust / venting system - Have stove and venting cleaned and inspected.
• Check Vacuum levels at the Vacuum Switch, with a Magnahelic Gauge (readings must be above .07”
W.C. on low fire).