Following advise from Steve at Fosworks I have double up on the chokes/supressors that were fitted to cure a problem of interference from the motor affecting the triggering of 2 sound functions on the Sierra card. When running light engine or on the rollers this problem seemed fixed with a single wound choke near the connector between the loco and tender. Out on the road with a load though the problem seemed to rear its head again, though in a more limited form. See the first video above, near the end, and you will hear the bells sound - all by themselves with operation of the programmed latched switch triggers on the Omnis 2 tx.
Well, I switched off the voltage activation of the bells (not needed I only want to trigger them from the tx) and followed Steve's advise - added a 2nd choke, placed it as close to the motor as possible (up tight to the motor inputs on the terminal block in this instance) and double wound the wires around it. I decided to retain the originally fitted device but doubled up on the winding of its wires too. Possibly a bit over the top but what the hell. Take a look at the picture and you will see the added choke hiding down below where the drawbar pivots.
Hopefully all will hunky dory.
Max