For twenty five years we hauled a Travelaire 5'er around - best trailer we've ever owned. In about year 22 the fridge also gave up and we were faced with the same dilemma as you have. I was told by more than one person to turn the fridge upside down to allow the chemical to recirculate. I never got a chance to test that as I was able to purchase a second hand unit very cheaply. In your case in might be worth a try. I found this written on the Internet: "Remove the entire refridgerator and turn it upside down for 24 hours. Then turn right side up again, let sit for another day and give it a try. I don't know how or why, but it seems to give them a new lease on life. won't fix an electrical problem but it gets the ammonia flowing."
"We were not placed on this earth to see through one another, but rather to see one another through!"
2013 Timber Ridge, 2013 GMC Sierra 6.2 L