Thank you Jon and GGG for your responses and suggestions. The coupler is still stuck in the open position. I am sure it didn’t overheat and it doesn't seem to be bent. I already ordered a new one from MTH Parts and installed it. I am happy to report that it is working normally.
Navigating and ordering from the MTH site was very easy. The parts schematic for my engine and tender was helpful in selecting the correct part number, and I easily found it on their parts list. It included a photo of the part, which confirmed to me that I had selected the correct part.
The service was incredible as it shipped the same day, and I received it two days later. My hats off to them!
Thanks again,
Ron