Ice build up causing fan to stop - fridge not...

GE Profile- TDC18PAABRBS - There is ice build up at the drain area causing the fan to stop. The freezer continues to cool properly, however the fridge does not. We have taken it apart a zillion times and made sure that the drain is not clogged. We have defrosted it several times and made sure that it was not in Defrost mode when it was turned back on. We have had a repairman change the fan twice and once he jigged with the fan. The problem continues. We are going to try using the front legs to tilt it back a little more and see what happens. I sense that this is a commom problem with this model fridge. I know it is old (bought in 2001) but do you have any solutions? We really don't want to have to buy an entire new fridge.