All,
Thanks much for the responses. GRJ the picture and diagram especially helpful - thanks for taking the time to post those. I'm traveling this week, but back on Friday and I will check it out. Couple of more questions since I am definitely not an electronics expert:
How do I check for a short across the diode? I do have a multi-tester if that will help. If I do have short in that diode, where can I get a replacement? I imagine it is something I will have to order, but from an electronics store or MTH?
In the meantime, can I set up the TIU to run my trains via the fixed 2 input/output? If so, how do I do that?
Thanks again