I have a mini kossel running duet electronics (0.6.x) with reprap firmware. Everything was working great for the last couple months when all of a sudden a couple days ago my steppers started missing steps. I've corrected the problem for now by increasing the current to the steppers with M906 from 400 to 1000. My 12v power comes from a 600w atx power supply. It's still delivering 12v (with no load anyway, I don't have a good way to measure under load).
Previously running the steppers at anything above about ~600 in M906 would cause them to overheat from too much current. Now they're cold to the touch at 400 and about 40c after a print at 1000.
Everything seems to be functioning now, but I'd like to know the root cause. Any thoughts?