Great response! Thank you for all of the replies. Here is what I've done:

I did check my receptacle for the TM and it is good with no voltage drop even under load.

My TM is a 12 volt and I have 2 Interstate TM Batteries in parallel bought less than a year ago. They are fully charged and maintained proper voltage under load and tried them both separately and they still maintained voltage, also under load.

I found the OEM battery that was in my controller when I changed them the other day: Renata 3V number CR2450N manufactured by Interstate Battery and available on their website for $3.99 each or on AMAZON for $3.64 ea. I found a statement online at Battery Mart that said: "This CR2450N Lithium Coin Cell Battery is 3 volt. These cells have a special groove on the negative side of the battery that is required for certain devices." So....I ordered a couple of them and will give them a try since I couldn't find anything else wrong.

I have charged my TM with it plugged in a few times however. This is not common practice for me however since I usually unplug it after loading the boat. That may be my next order of business if the Renata Battery doesn't do the job.

Thank you all for the replies and if anyone else thinks of anything please respond. I'll will post the fix when I find it.