Funny you should mention glue, I have a distinct impression that some of the failures are due to a sufficient quantity of glue. I've had a couple of bits fall off at the slightest touch and looking at them closely, 'glue' doesn seem to be present in what I would use in those situations. BTW thanks for all the investigative and remedial info. Much appreciated. I had a slight accident with my 'Exe' when I was milling out the body for a sound decoder, nothing that cannot be fixed but I'm having to find a paint match for the green. It WILL go in.
Mark K