Infrared temperature gauge used to analyze motor problems?

I have used the Raytek MT6 shown below for about three years now.  It is useful and provides interesting information, but you have to learn what the baseline of heating is for various locos.  It is very easy to use.

This has helped me diagnose and find only one problem.  I had a WBB Tranmaster that had what I suspected might be a burned out motor (eventually it did).  With the shell off I turned on the power to the loco, the one motor would not turn, and I watched it with the temp sensor: it got hot quickly, not so hot I could feel it for sure, but this sensor saw it, verifying that the motor was getting power, and was the problem.  

However, this helps alot to verify there are not problems and that trains are not overloaded.  Again, you have to learn what normal is.  I have learned that with Legacy of Premier locos, the loco gains only 3-4 degrees of temp rise in the shell when running normally, and that that takes a while (alot of metal to warm up), but that often the tender, nearest where the electronics are, warms up as much as 8 degrees.  If a loco is warming up more than that near where its motor is, then it is probably pulling too much. So it is useful to verify if I have my doubts.  For example, it is easy to overload the scale Lionel conventional Hall class (Harry Potter) loco, with its small motor, and you can definately see the temp climb if you ask that puppy to pull to much (be careful trying it, by the time the motor shell is hotter by eve a few degrees the motor is cooking nicely).  

Thanks Lee for the reply and great info! I might just buy one as it was only $25.00. I envision using it in many areas and not just trains.

Another use for this unit on our trains would be to see if a smoke unit is heating to proper temperature. I sometimes get a little carried away with ideas as I can imagine a box car or control panel that would give you continuous temperature read outs as your train moves along. To me that would be very cool! (no pun intended)

* I ended up buying the Raytek MT6, like the one you have Lee. It was a little more money than the other unit I described.