I have 2 green bcm's here and both occasioally play up and need a "tap"..... Why is it that they play up? I have a mate who use to be a radio tech and a computer tech and he would be able to do any circuit work needed, just dont know why they do it so I dont give em to him and say "here, dont know what the problem is but fix it for me".

Well they are getting old - aka mid 90's age, so solder joints crack, dust ingress helps with over heating of components, etc.
I've been lucky with BEM's, haven't had many probs at all.

Having said that, I'll most likely replace my EF BEM's with EL ones.

If you have a look at a EL BEM cct board, much smaller and more rationalisation/better components.