Thanks for you post and advice, mchero.
You were right about the placement of the two fans on our unit. When we pulled out our fridge we checked them (I didn't even know they were there!) and they were working fine, but my tech guy also said it wouldn't hurt to put a small fan in the outside compartment door at the bottom of the fridge blowing upwards -- to supplement those small 4" factory fans -- allowing them to pull out even more heat. I'll do that, too.
BTW: our cooling unit fix is now complete and the fridge is working great again. We bought a Norcold factory replacement cooling unit, so it is guaranteed for a year, + labor is included if something happens.