Here’s a thermal view of the controller while operating. The hotter one is on the right side of the board (looking at it), which controls the left side motor on the Maslow (Port 3). I suppose this one also controls the Z-axis (Port 2)?, so it makes some sense for it to be hotter?
Temperatures of both chips seem to be about the same - about 172F, so the heat sinks are working, but the right (Port 3 side) one is working harder than the other one, for sure.