I realise that now Mike. Xtal changing is an accepted legal practice in the UK and generally we have few problems. But often suppliers will supply alternative makes of xtal.

My problem with the servo movement appears to be related to the servos (Jamara 9gm). I have tried a second servo with my Hitec mini rx and the result is the same. Sometimes the servo only moves in 1 direction but sometimes works in both directions.

Will try the feather receivers with my hitec servos to eliminate them as the source of the problem.

thanks for your help.