haeh

It's an old thread so sorry to reply now, but since I was directed here from google when searching about the slow boot of UM2+C, it's worth correcting the statement above. The UM2+C does NOT run linux, but just a version of Marlin. If you check the schematics of the mainboard used, the microcontroller used is an ATMEGA2560, which is WAY WAY too slow to run any operating system. It runs just Marlin, and it's also not particularly good at it, if you consider that Marlin above a certain speed starts sending steps to the motors not uniformly, but in groups of two or four. Check "marlin double quad stepping", which starts happening at 10 kHz, which means for the UM2 series 125 mm/s. So we don't know why the UM2+C is so slow, but it's not linux.

You should optimise the "flow" of the eSun, since Ultimaker provides optimised profiles. Either you use Orca Slicer instead of Cura, which provides tool for said calibration, or you follow Elli's guide https://ellis3dp.com/Print-Tuning-Guide/articles/extrusion_multiplier.html or you simply use the Ultimaker ABS profile for eSun as well.

Could someone please post a list of checks that should be performed on a second hand printer, assuming personal inspection is possible? - rattling noises overall - screeching noises like damaged bearings when manually moving the print head - solidity of the print bed and rough alignment (not bent, slanted, ...) - working display and similar accessories (camera, control wheel, ...) - test print: no clogs, no underextrusion - bowden tube: visible wear, solidly fixed to the print head Anything else? Is there a non-resettable counter of the hours of operation? Thank you in advance