Update:
Firstly I tried disconnecting both motor cables, pressing both buttons simultaneously for 5-10s and then reconnecting the cables -> no change and still would not go beyond 39E.
Then, about 20 mins later, I set the TD110 to Thor with the TM, and then tried simply pressing both buttons simultaneously for a few seconds without disconnecting the motor cables, and the motor then moved W with both buttons pressed, and so I exercised it with the E & W buttons for a few seconds each and it went in the directions that it should. Came back indoors and, with the TM still connected, sent it to several sats and so to 39E, and then tried to move it further E - and it now goes to 52E with no problems!
On reflection, I'm thinking that, good as it is (has the most sensitive tuner of the boxes I have) the FreeSat 7HD seems to have been the common factor in the issues with both the Dark Motors when driving them to the E - has only caused the issue once with each motor, but I suspect that, at times, it sends signals which corrupt the motors' stored sat lists.
Possibly doesn't help that I now have 10 LNBs on the fixed dishes connected to the 10-1 DiSEqC 1.1 switch, and the receivers are set up with both the 1.1 LNB switch positions and the USALS motor commands for the full dish arcs. This means that I should be able to swop the cables on the receivers to the dishes and use either one of the motors, or the switch, as required (that's why I fitted the R/C controlled cable switch in the lounge system). Thus, maybe, sending both 1.1 and USALS commands (consecutively, I assume) can confuse the motors, even though, IIRC, that the latter should ignore the 1.1 commands?
