Defective Kenmore Upright Freezer Model 253

We have five Sears Kenmore Model 253 upright freezers purchased between 2003 and 2006. Within the last year two have failed due to the same problem. A power transformer for the compressor has burned out in both cases. A service call was initiated both times and the $26 part was replaced for a total of $223 with labor. The replaced part is visibly melted and burned. The service man seemed very familiar with the problem and thought it likely that he would eventually be back to repair the other freezers. If Sears is aware of this problem with the defective part, why don't they do something about it? Also, I am concerned that a defective part in one of the other freezers may start a fire when it goes.