RM212f absorption fridge not cooling?

I come here out of pure despair. I own a RM212F fridge (3way fridge) from roughly 1989 in my camper and It does not seem to cool anything inside the fridge.

I tried the following:

1. Clean fridge rear removing dust etc
2. Clean flue and gaspipes en blow out the vent for gas to be able to pass ( Yes it works on gas and has a good blue flame!)
3. Checked both the 12V and 230V heating element and they both work.
4. Everything gets hot, YES!

5. Yet the fridge is not cooling. I tried to turn it around, leave it for a couple of hours (10) , then turn it back around and try it again, yet no real result and I can't say if it is actually cooling or not. When I turn it around I do hear a little fluid moving, not like a lot but like a little at least, I don't see any ammonia leakages mostly these fridges are welded pretty solid .. Doesn't seem as if the inside is getting cold at all. (even after like 12 hours not much happening). I put sme beers insidde and some water. I tried the highest setting and now trying a very low one (forum people told me sometimes it works only on a low stand?).

I'm so frustrated, I have been going on for like 4 days on this fridge.. I'm actually going on a holiday this monday so You can assume my frustration when I find this out just a couple of days ago.

Any advice would be lovely and immensely appreciated. Checking this topic on a regular basis and will post if I find a solution for future viewers!