TMCC Antenna

If it's temperature related, I'd consider swapping out the R2LC first.  If it were simply an antenna issue, it wouldn't be temperature dependent.

Dear Gunrunnerjohn: Thank you for the tip. But in my ignorance  I don`t know what R2LC is. Sorry about that.

The tmcc system uses modular boards in the later units like yours.  There is a radio receiver, a motor driver, and two boards for the sound (one is the sound board, the other the amp for the sound board.  RL2C is one of those and its the radio receiver.  There is also a chance that the antenna wire was not connected properly and that heat in the shell is causing something to expand and either lossen it more or possibly allow some contact with somthing that compromises the signal.

Chuck,

You mean like a bimetal thermometer?

Ralph-RJL

Chuck, while that's certainly possible, my bet would be on the R2LC.  I think I'd swap it with another unit and see if that solves the heat issue, it's an easy test.

I'm betting on a loose connection, probably something with a poorly installed wire nut.

No "thermostat" parts in the shell.  Something as mundane as a piece of antenna wire making contact with almost anything else that's made of metal inside the shell.

When troubleshooting circuit boards and other electronic components for possible heat related problems I use a freeze spray.  It quickly lowers the temp to sub zero and pinpoints the problem.  Here's what I use and keep on hand. 

I think I'd classify heat sensitive and thermostat parts in totally different categories.   FWIW Nick I use cooling spray for this kind of issue as well.  However, if you have another locomotive with a working R2LC, it's simple to swap them.

I look forward to seeing what this turns out to be.

You can also make a longer, more effective antenna from the foil strip used in assembling stained glass.

All of these things may be beyond the OP's skill level, though.