I’ve finally started moving on getting my SLB working, and I’m experiencing similar behavior. Lots of variables since I hadn’t completely dialed in alignment, but I was able to jog Y forwards/backwards in 5mm steps without any problem, but any rapid movement immediately stalled the Y motors. I dropped my acceleration down to 300 and this ‘seems’ to work - I’m able to rapid now - but I only got to this point late yesterday and so much more testing is needed. I’m hoping to spend some more time on it today. (I didn’t change my speed settings, but my rapids are short enough and accel low enough that I’m not getting anywhere close to max speed anyway)
I will add though that I originally had my machine set up with an XPro V5 controller, and while it was somewhat less fragile than the SLB, I also ran into Y stalling problems. So, this doesn’t seem to be unique to the SLB (but, the XPro is also a 24V machine)
There is another thread going here: X-Axis Stalling on Y1 Rail getting misaligned where tKC was experiencing Y stalling problems with his Pro machine even with the BB-based controller. The diagnosis there appears to be that some Pro machines shipped with incorrect motors, and I have the same model motors on my machine. Whether this is a real problem or not remains to be seen.