Pulled out my almost untouched 1950 773 to show a friend the other day. Smoke had died, smoke was sluggish anywary. I about burned my hand on the rear pickup roller after running it. 73 years I guess it may need a little more than just oiling.
Checking wiring and so on, found the rear roller 2 ohms resistance. Internal Corrision, oil, who knows? It was the original with a fairly deep groove. took off the pickups, cleaned all the oil off of them. Then replaced the pickup rollers. I checked them with the ohmeter also, they look good now.
Opened the smoke unit. Original resistor had died. It was not a flat mica plate, but had what looks like a bakelight piece on top of the flat mica plate. Haven't seen one like it in any of my other Postwar engines. All my other postwar engines just had the flat mica plate. Upgraded to liquid smoke unit.
Original smoke unit
Test ran, the smoke bellows wouldn't come down. Checked it, someone had oiled it. It was oil, not smoke fluid. It just stuck at the top. Cleaned it and added a smoke unit spring.
Checked the gear box, not bad, a little shy on grease. Fixed that. The Engine, light, e-unit and whistle are still doing well. All original wiring in the engine except the smoke unit now. Ran it and it puffs pretty O-rings. Can't hear the motor. Quietest of all my post war and quieter than my modern engines, except the new can motor diesel. Just a joy to run again.