One of the issues with the way Bailey construct their electrics is that there is often little or no air flow anywhere around the power box in the top of which the power supply unit (PSU) is located. There is a small fan in the PSU but that often either fails or gets stuck with fluff.
The simple answer is to get two small 12V computer fans. Fit one over the grille in the plastic of the power box at the top of the left side wall, setting it so that it blows air into the box. Then fit another over the grille at the right end of the top panel of the power box, setting it to extract air. (There will be arrows embossed on the fan body showing direction of rotation and of air flow. Wire the fans in series so that they run slower than normal (and thus quieter) and connect then through a switch to the 12V supply. This will keep the power supply cooler and extend its life expectancy.
Incidentally doing the same with two fans behind the fridge cooling vents so that the lower fan is blowing in and the upper fan is sucking air out and you will never have any problems with your fridge failing to cool no matter how hot it is outside.
I can't remember if it has been mentioned, but the PSU is supplied by a mains 'kettle plug' and they are notorious for falling out in transit. With the mains off, first free the power box from its mounts, then undo the four screws on the front panel and remove the front of the power box case. The PSU and kettle plug will be obvious. Make sure the plug is pushed fully home and fix it in place using a couple of long plastic ties in series round the PSU box (the box just pulls out once disconnected.) Reassemble in reverse of disassembly.