i have 1956 ge refrigerator model LM11NC serial ON666983. was my grandmother's new. i remember being only tall enough to look over the vegetable bins. I have had it since 1982. runs fine, except lately last ten years will ice up rapidly on the coils inside the refrigeration compartment. freezer compartment will also fill with ice. had refrigerant checked, it is fine. relay works and compressor cuts in and out. have replaced thermostat with a universal model 3 times. first time in 1988, and worked ok. last two times icing is getting worse. i would like to keep this for sentimental reasons, and it is in terrific shape. what do you think i can do?