https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/5227

https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/5209

Only suggestion to try so far is disabling "Avoid crossing perimeters".  I haven't tried it yet.

Posted by: @rickster

Just updated to 6.5.3: It also updated the loader to 2.60. When the bed traverses from the front to back (y-axis), it hesitates. Kind of like a hard hiccup or a stutter. Reverted back to 6.4.0 and the problem disappeared. However the loader didn't revert back. Also getting a message from Prusa Connect that the printer needs attention. Before the update, I was happy with what I had. I should have left well enough alone.

This I think I am seeing as well, but both on the X and Y axes.  It seems to start and stop (or maybe just hesitate) a few times on a long fast travel.  I hope it's not a performance issue where the controller isn't keeping up with the motion...

The quality of prints that roll off of the latest Bambu Lab printers consistently exceeds that of the MK4S.

Not really, it's a mixture of advertising hype and genuine reductions in the amount of maintenance required to preserve quality.  In practice there has not been a noticeable increase in print quality from a properly tuned Mk2 to any current FDM printer with the same filaments. The Mk2 generation exceeded the precision required to extrude within the possible accuracy of the common (and practical) nozzle diameters and no advances can improve on that.  OK, speed, overhang performance, a greater range of printable materials and many other peripheral improvements have accrued but basic print quality, no.

That said: after being left unattended for a while bedslingers and other open architecture printers usually need surface cleaning - dusting and cobweb removal - especially the smooth rods, followed by lubrication.

Cheerio,

BTW, these are the changes in 6.5.3 that apply to the MK4S.  It's disingenuous to say they've dropped the MK4S like a hot potato.

New features and improvements

• Massively speed up MMU filament changes
• Preload all MMU slots at once

Fixes

• Fixed layer shifts during high-speed curved moves M1704
• MMU load test gcode now considers toolmapping
• Fixed MMU sending spurious attention reports to Prusa Connect during normal toolchanges
• Fixed crash/BSOD on M501 (restore settings) (#4912)
• Fixed gearbox alignment test showing wrong status when skipped

Call me a fanboy, but....  well, maybe I am!  I bought the printer in the first place (my first and only printer BTW) because of Prusa's reputation for quality, support, high standards, and openness.  I'm convinced that openness is why so many people get frustrated with them, because they hear about the next new thing and expect it on their doorstep in a week.  But Prusa talks while they're developing, not when the user manual is done.  And I've been extremely happy with it.  But like any technology (ask me about my Macintosh journey since 1994) there will be jumps in technology that cost you more, and some that are less expensive/drastic.

I'm confused why people are expecting effort to continue on the MK4S when there's a clear upgrade path to a MUCH better technology.  I expect the Slicer and firmware to continue to be supported, but please don't spend much more than 0.5 HW dev (maybe train interns) on new hardware for the MK4S!

And BTW, where will 3D printing get their advances if Prusa is gone?  You think Bambu will sink tons of R&D into leaps of performance?  They're much more likely to chase profits than progress...

I don't know why I'm rambling - feel free to disagree, I always listen, but I might not change my mind...