My ancient GE TBX23ZHB is failing. The freezer's cold, but the fridge isn't.

After reading Costco reviews for new ones, I'm going to try to get my old one repaired.

I'm using a Taylor Fridge thermometer. Here are the temps:
Freezer temp: 0-degrees
Fridge temp: 52-55-degrees (turned to highest setting)

• I clean the coils every six months. I checked this morning and they're 90% clean. I got very little crud from the tapered brush.

• There's no ice build up anywhere.

• I did the bill trick: It's difficult to evaluate what's "difficult" or easy. I could pull the bill out easily -- there was little resistance.

• Last year the bottom fridge door seal detached from the door was hanging. I cut it loose and replaced the entire area with a Home Depot weather insulation strip. The seal seems good there and everywhere else. I used a Harbor Freight temperature gun (you know, with the laser beam). I ran it across all the freezer and fridge seals. The readout shows numbers between 83- and 86-degrees.

Thoughts?