Refrigerator compressor not always coming on, freezer thawing, compressor starting hard (kluncking) intermittently

The klunking compressor had been a symptom for a few months and I changed the start relay on the compressor. It was better but still an occasional problem. When the thawing freezer began last week we called in the appliance company. They did not discover the problem and two days later the refrigerator would not run at all. Suspecting a bad thermostat or defrost timer as the two likely options I ordered both and installed them myself in less than an hour. Defrost timer instructions a bit hard to follow as the timer is made to fit several configurations. The refrigerator runs perfectly now and the klunck is probably gone too because the compressor is getting full current. The cost of the thermostat and defrost timer was $90.00, the same cost as the unsucessful service call.