Problem solved!
Thanks to Colin (Atmos).
I added a washer between the filter wheel and the filter body as the retaining screws for the filters were too long and protruding out and scratching the filter wheel body. But by adding extra distance between the filter wheel and the filter body, the homing and the position sensor cannot accurately position the filter wheel.
Solution: Colin gave me a pack of extra washers to keep the filter retaining screw in the filter wheel. This allowed me to remove the washer between the filter wheel and the filter body, and now the sensors can work on the wheel.
So I can now connect the EFW to Sharp Cap, Sequence Generator and Maxim DL.
I will now write to ZWO to ask them to add extra washers in their EFW packs.
Bo