Successes and failures with the MK4+MMU3

Status after 3 weeks of using my Prusa MK4 with the MMU3.

I think it is important is share both good and bad experience, and their ratio:
• Successful prints: 28
• Failed prints, my fault: 4
• Failed prints, hardware/software fault: 1
• Filament loads: 1720
• Filament interventions: 2
• Print time: 4d23h

My success rate has been quite good. Especially since I am counting all attempts, include those where I learnt what not to do. This is my first MMU, and I am printing primarily in 6 year old ABS.

My conclusion is that: Not only is the MMU3 very reliable. It actually improves the reliability of the raw MK4. Which means I no longer need the babysit the printer, to make sure first layer calibration goes well. I can just start a print and go to work or sleep.

Issues with raw MK4, fixed with MMU3
[1] During print start. The pull-force required to pull down the print head, with loaded filament, can bee too high. Resulting in the print not starting.
[2] Oozing causing the first layer calibration to halt.
[3] Oozing causing the first layer calibration to fail.

Consequence of issues
[1+2] Results in one can return to a print after 8 hours, which has not started at all.
[3] At best gives a poor first layer, or at worst covers your print head in wasted filament, and possible breaks some parts in the print head.

How is it fix with the MMU3 added
[1] Has been fixed by having a PTFE tube between the print head and the MMU3. So no extra pull force is required while the print head is being lowered.
[2+3] Has been fixed by removing oozing, by not have the nozzle loaded while doing the first layer calibration.

Source files for all my success multicolor print: http://cablecat.dk/mmu