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Due Controller with 2 heat sink board - no fan (don't do it - even though it calibrates)

I have a version 1 Due board with 2 L298 chips, so one of the primary left/right motors shares a driver chip with the Z axis. It works fine to calibrate, but I was running a 10 pass cut and about pass 7 the shared chip got too hot and the sled continued to move in the correct general direction, but it began oscillating vertically about 1/2" as it went, so it was kind of hopping. I’ve now seen this twice. It happens after a long run time. I recall another user posting about this and I responded thinking it was the sled catching or something mechanical. I believe now it is the motor chip overheating and going into failsafe mode or some weird state. The good news is that it recovers after some time left alone to cool off.

After having this happen twice, I just wanted others who have a 2 chip motor board to be sure to fan cool so you don’t end up where I did with a lost home position, having to reset and restart a project.

do the 2 chip mega boards with the L298 chip do the same thing?

I think that’s exactly what’s happening. The chip is throttling power to protect itself and in the process not delivering enough power to the motor to keep up.