You broke your end stop flag it sounds like. It is a small piece of plastic that should be sticking off the right side of the carriage. That "rumbling" is your carriage slamming into the side of the printer and the teeth skipping on the belt. And BTW you have your axises mixed up the y goes forward to back and the x goes left to right.

Thank you for the information, browning! I will check if that is the case and look into replacing/repairing it somehow if necessary. What got me suspicious was that at the end, the carriage would home in on the "start" position without problem and without slam-skipping.

I have a Da Vinci 1.0, and I recently forgot about the "Y axis first!" rule while using jog mode. This caused my X axis belt to jump. After that, at the beginning of each print, before the bed has even started to rise, I get these terrifying grumbling sounds for several seconds. I assume this is somehow caused by the skip (the X motor trying to adjust the extruder even though it is actually at (0,0)?). The print then goes ahead and completes just fine - it gets centered well on the bed. So, the two events might not be related after all. I don't print very often, so I have only observed this twice so far and didn't think to look at the head while it is happening, so I can't give more information.

Any advice on how to fix this issue, or how to troubleshoot it - and whether I am correct about the cause? Thanks in advance!