Hi Smyth, well, being the internet, the whole picture doesn't always come across. When I think about it, I recall having problems binding with my Apprentice long ago as well. I think I wound up using a switch harness with a separate power supply for some reason, then it worked. Probably pilot error. (Me doing something dumb.) Though you say it binds fine again with the 5e. (Did it lose bind in the first process?)
Stupid question: Are you binding per the manual?
You said you tried multiple cables. Were they Spektrum cables?
Sorry if these are going really basic here, but it's your first post and I don't know how much RC experience you have.