I bought the digital multimeter, which, as you suggested, is much easier to read. It came up with 12.9 not hooked to AC and 12.95 to 13.05 hooked to AC.
But then, for a reason I don't understand, the TT worked just on the battery. I am not feeling this is a solved problem because I did not really do anything. When I took the battery off yesterday, I needed a wrench so I don't think it was a loose connection. I was looking for a fuse yesterday and therefore moved some wires. Perhaps that was it? Either way, I am going to keep an eye on it.
Thanks for the help with the multimeter. I appreciate your time.