Selecting any Menu to handle Filament - Left front motor ONLY starts lowering bed causing issue.
When selecting any menu item under the filament menu the bed usually lowers some (not sure of the exact amount or why). Sometimes mine only does the left front motor and then the bed is unlevel and jams. I have to manually "eye" level and then select the Auto Home to realign. Prints are perfect and this does not happen every time. Usually only after power on cycle. If I do not have to change filament this does not happen. It only happens when the bed is lowering to change or load a filament. Again, I am not sure why the bed lowers every time you select change or load filament - doesn't make sense to me, but I am not an expert by any means. Just a hobbyist printer. Any help would greatly be appreciated.
RE: Selecting any Menu to handle Filament - Left front motor ONLY starts lowering bed causing issue.
The fact that the firmware keeps moving the bed down for various filament loading and unloading steps in indeed annoying. I can see the point of doing it once if the printer has not yet determined its XYZ positions by homing: The firmware moves the print head to an XY position where the PTFE tube is relaxed, for easier filament insertion. And it needs to make sure that this XY move does not damage the print bed, hence moves the bed down. But the firmware should remember when it has done this safety move once; there is no need to repeat it afterwards.
Your heatbed may still be tilted somewhat, leading to the occasional motor jam upon these moves. "Auto Home" does not level the bed, it only determines its position by touching it against the nozzle. You will need to run "Control > Calibration and tests > Automatic Z calibration" to get the bed leveled (by driving it down into the end stops, noisily).
An alternative cause for the jams might be too much lateral strain on the trapezoidal nuts. Their position is over-constrained by design; it needs to align with the bed position defined by the smooth rods. You can do the following to make sure the nuts all sit in "relaxed" lateral positions: Drive the bed all the way down. For all three black trapezoidal nuts at once, loosen the two M3 screws that hold them to the bed. This lets the nuts settle in the correct lateral position. Then retighten the screws -- do not over-tighten, the nuts are plastic (POM).