Truma Combi removal on Warwick Duo

Hi All,
The Truma combi 4E on our 2012 Warwick Duo refused to work on any mode on our first trip for a little while this week. It was very cold! The flash code on the l.e.d. on the main circuit board on the heater itself indicates the combustion air motor is taking too much current.This must be part of the 'pre-flight checks'. Even on 240v mains the boiler fails after approx 30 seconds with flashing red light on the control panel. 
Anyway, I've removed the air motor and it seems to be absolutely fine and runs and spins freely. Wiring harness also seems fine. Next check is the main pcb on the unit. Unless anybody can tell me different, I feel sure I have to remove the whole unit from the van to remove the pcb for testing. Unless anybody tells me different, this means drilling out the rivets to remove the hinged bed base to make a big enough hole to get the Truma through. (Yes, the hinges are riveted onto the steel frame).
Thought I might just replace the air motor and pcb but £240 and £238 respectively!
Have any of you removed a Truma combi from a Warwick Duo , or indeed removed just the pcb and can give me any advice ?
Thanks, Tim