Just dug my Airfix B set out and dismantled a coach. The interior molding is screwed to the underframe. There are three lugs on each side of the interior moulding which engage with 3 slots on the bottom of each window molding which in turn are glued to the inside of the body moulding. This sounds complicated but all you have to do is carefully run a fingernail along the bottom of the body moulding where it sits on the chassis and gently pull it up - do this on each side until the body moulding is free.
What I did was to fit Bachmann metal carridge wheels which are available as spares and which are very free running in the Airfix bogies. The coach runs very well and freely like this - makes very realistic noises over rail joints as well! I did the same to an old rake of Airfix suburban coaches - they had the small Airfix coupler (like the latest Hornby/Bachmann design) and it might be ok to fit this to your coaches as well. Made a very usable rake that had the feel of an old suburban train (well, to me anyway).
Hope this helps.
Bill
What I did was to fit Bachmann metal carridge wheels which are available as spares and which are very free running in the Airfix bogies. The coach runs very well and freely like this - makes very realistic noises over rail joints as well! I did the same to an old rake of Airfix suburban coaches - they had the small Airfix coupler (like the latest Hornby/Bachmann design) and it might be ok to fit this to your coaches as well. Made a very usable rake that had the feel of an old suburban train (well, to me anyway).
Hope this helps.
Bill
