Gearbox alignment

Note that the gearbox alignment on the Prusa XL is only available from FW 6.4.1 onwards, which is in pre-release still.

I really wish there was a video of this online -- this is _very noisy_ for me and I can't tell if it's a reasonable amount of noise or not. I have been debugging an issue with my Extruder motor, and already received a replacement for that, but the issue persists.

6.4.0 for XL has really bad layer shift and is not available anymore.
There is no gearbox alignment option for XL at the moment.

Used Ninja Flex and could not unload. Used Ninja flex before couple of times. Excellent support, guided me through this first time experiance not working of unload. In my case, i had to fully remove nextruder with gear. Did use the gear allignement tool (E1) which came with the MK4S upgrade Kit and makes the critical adjustment much easier. I did trust the 1.5 turn instruction and final adjustment did work. Using my MK4 since 2 years with lot of prints, upgraded 1 year ago to MK4s. I had a situation where i felt the 3 screws does not fit anymore perfect. Thats was solved once i did remove the hole assemebly and re-assembled it back.

As someone noted in the comments of the Core One assembly kit: When the on-screen instructions tell you to "lightly" tighten the screws, they should still be snug. That is, they shouldn't be so loose that there is any play or that they work themselves out over time due to vibrations. Not doing it correctly was one source of random Z-banding/uneven layers on my machine that got worse over time, as the screws loosened. The point is that you shouldn't over-tighten anything. Not sure if the calibration detects it and warns you if you cause the mechanics to bind up or not, but finger-tight (using the small end of the allen key as a handle, putting only the lightest tension you can on the handle) seems enough.

One thing that isn't immediately obvious is that these screws are the only thing that fix the E-motor and gearbox assembly in space, relative to the extruder carriage and nozzle, so if there is any play in it, it could put uneven pressure on the filament, giving small variations in the extrusion.

I agree with the others about the directions on screen being contradictory when loosening them as well. Does it mean the top of the screw head should be flush with the cover plate, or the bottom? If it's the top, that's not possible, since unscrewing them 1.5 turns makes it poke out more than that (about half a millimeter, maybe). And making the bottom of the head flush would require significantly more turns. What I did was to follow the "1.5 turns" instruction and trust that. Maybe they mean you should pull out the (now loose) cover to make it flush with the screw heads?

In any case, after tightening them down again, the top of the screw heads are slightly below the surface of the cover. Not much, but half a millimeter at most.