Finally plucked up the courage to put the power leads to the Terrier chassis this morning and low and behold it worked! Apart from the gear slipping (now secured with Superglue) it’s all systems go.
Also took the J71 chassis out of the box and applied the power to that. Ran ok and thanks to graham Shirley don’t have to worry about the coupling rods as they are on.
Onwards and forwards – happy modelling!