Sorry for the very late reply.
I have been so busy have barely had time to sit down.
This pic, I have 3 exactly the same remotes
That is definately the remote for the FF Thomas. I would troubleshoot by taking the tender apart and Test the battery to engine. I have made a battery pack with alligator clips to do this type of thing. As mentioned a couple of these I have fixed simply by taking them apart, testing and putting right back together. Also could be the motor. You could try touching the positive and negative to the motor directly to test. Let us know how it goes.
Thank You good idea's.
No time off until Next Thursday or Friday, so will definitely try this with my partner as it bugs me too buggery that they do not work!