A friend of mine has a Daewoo machine with a Mitsubishi MDS-A-SP-260 drive for the spindle. The drive works fine when lightly loaded, but when loaded more than about 35% for 20 minutes the drive shuts down on alarm number S01 003B. The book says this alarm is "intelligent power module" (IPM) overheat. When this happens the heat sink on the MDS drive is barely even above room temperature so it appears to be bogus. We have replaced all three power modules and the problem has not changed. Does anybody know how this temperature is sensed? Any idea what to check next? Thank you.