Fridge is an easy fix, there is rust inside the gas burner box at back and needs cleaning. Rarely is rusted out because not exposed to big flame.
Heres how to fix. Photos I used are from google images. Your fridge won't be identical, but will have same pieces.
Take out fridge
Take note of electrical connections on top.
Remove the panel on right. Is held in with 1 or two rusty screws.

Remove the burner box. Take note of the position of the ignition thingy (also can give this a light buff with some VERY FINE sandpaper. Just a little bit) and don't bend anything.

Blow out and clean up the box out. Should have some nice flaky rust in it.
Cleanup dust and any muck where fridge was, + fridge itself. Refit fridge.
My fridge stopped working and I did this, blew the box out with my own breathe (thoroughly mind u), cleaned it up some and .. jobs a goodun. Went from rarely if hardly starting with yellow sooty flame to nice strong blue reliable flame, on the first attempt.
Whilst you have fridge out, leave it upside down for 24 hours. Presuming all the gas hasn't leaked out over the years, doing this will unsettle all the gas and (hopefully) let it get cold again.
Good luck.
Livin' in me van in Portugal.
'93 Mk4 TD 150L Hitop Custom Camper
100ps Epic blue spot