Thetford N80 Fridge

Fezzer

Hi, I have a Thetford n80 fridge which seem's to have given up the ghost. You can hear the fridge making the usual noise when it was working correctly but it is not getting cold at all on either 12v, gas or electric. I removed the fridge and on investigation
noticed a yellow   (dry) substance just behind the fridge. I have researched a replacement and cannot believe how much a replacement new fridge costs. What I would like to know is, is the fridge repairable or if not could you please recommend anywhere for
a second hand replacement. Thank you.