Yesterday, I removed my Legacy system from the layout to take it to my office and connect to my Windows 10 PC to upgrade to v1.7 using the Legacy System Utility. Since my PC has a serial port, the connection was easy, a black module was created and loaded to the Cab2 remote successfully.
While the Legacy base was not on the layout, I powered up the layout and two Legacy locomotives (using 135W brick transformers connected to a PWC ZW) came on in conventional mode. All seemed fine and I did what I needed to do and thought nothing of it. Later, after re-installing the Legacy system back into the layout, when I powered up my Lionel 6-38419 UP U30C (cab 2918) locomotive (that had started up in conventional prior) , it made an odd whining sound, ran for a while and stopped. RailSounds also stopped and the whine continued.
I took it into the workshop and started to remove the shell to take a look inside and was unable to locate all of he screws to remove the cab. Then I found an old post from 2013: https://ogrforum.ogaugerr.com/...rews-to-remove-shell. Even one of our top repair experts commented that he was in no rush to work on one of these!
Thinking this was beyond my capabilities and knowing that sometimes trying to fix one thing results in breaking two others, I emailed one of our forum members that is a know Lionel repair expert asking if I could send the locomotive to him. Later I had the brilliant idea to get out the manual and do a Legacy reset and voila! The locomotive is back on the right track (so to speak) responding to Legacy commands and RailSounds working without that odd whine.
I immediately called off my request for help and apologized for the first email.
Moral of the story - try a re-set first before panicking!
