Magtech amplifier over heating.

I bought a magtech amp a few years ago and have had to send it back twice in less than a year. The Motorola thermal track transistors are not reliable. When the thermal sensor goes the amp will become very hot even in idle. The left channel failed back at the beginning of 2015 and then the right channel failed in October.The amp still worked but the heat sinks were very hot even at Normal listening. Roger has no problem with fixing the amp. But how often is this going to happen. I have an Aragon amp that I've had for 30 years and only had it repaired once due to my negligence. Has anyone else have this problem.