Thanks Dennis, next time I have one apart I will try the spring. Being in California we are very limited as to the solvents we can get. I have gone to acetone for a residue free cleaner. But I have yo be careful where I use it as it will go after some resins.
George, I checked Bob Hanson’s book and he says the coil resistance is 12 ohms, so I think your in the neighborhood. Other places to watch are the ground return path. That bell on/off switch is in the ground path and can be a problem. On maybe half of the 227 switchers I work on there is a phos bronze strap between the back up light board mounting bracket and the frame. That strap goes across the top of the truck mounting pin, giving a direct ground path from the truck to the back up light board. That modification or running change always indicated to me that Lionel had trouble with grounding on these tenders. I have not seen this strap on any of the post war tenders where there is a ground wire to the engine.
On the thermal switch contacts, frequently the eyelet that mounts it is not so tight that the contact can be swung sideways a little to give access to the contacts for inspection and polishing. If you do this be really careful with the ni-chrome wire going to the ground point. If it breaks it cannot be soldered and reconnecting it can be a bear. There are several places on that board where contact is made with parts just clamped with eyelets. You might want to jumper some of these and see if any are high resistance connections. I do not know if you have noticed yet, but that ni-chrome heater draws so much current that it causes the back up light to dim when it is in the circuit. You can use this dimming when the engine is pulling the tender around the track to see if the contact is opening and closing and if the bell is ringing at the appropriate times.
