The recent purchase of an old Commodore Vanderbilt (NIB) brought some disappointment. All the features but one worked...it wouldn't chuff. It would go through the motions during start up...chuff a few times then quit. I immediately suspected the cherry switch which I've had issues with in the past. No biggie... I was planning an upgrade to 4CR anyway. Diving into the modification, I discovered the switch to be good but went ahead and attached magnets to one driver and installed a reed switch. End result was as expected...still no chuff.
A curiosity found on some of these early TMCC engines is the optional feature of a CC coil coupler. One comes as a replacement for the factory installed regular coupler once your layout was upgraded to TMCC. So I set about removing the tender shell to attach the coupler wires. The battery compartment in the CV tender is accessed from outside so unless you were performing the coupler change there's no need to take off the shell. Once opened, there, looking as obvious as an exploded capacitor, was a blue wire from the tether squashed flat by the tender shell and chassis. Chuff fixed...Easy Peasy!
Bruce