You may be interested in these links, it can reduce or eliminate the problems which require cold pulls. Basically the issue is that the tubing moves up and down during printing and creates a slack space where the filament gets into a region of the nozzle it’s not supposed to reach. This modification uses a short length of tubing inside the nozzle that is pushed down tight, then your regular tubing sits on top of that where the movement doesn’t cause any problems. I’ve never had a single clogged nozzle or needed to do a cold pull in several years since making this change, so I highly recommend it.

https://www.youtube.com/watch?v=7tCxO17XZtw https://www.thingiverse.com/thing:4220059

Honestly at that point I would tear down the whole thing and use this video as a guide for reassembly. The most important thing to do is to make sure the framework is all squared up, otherwise all prints will suffer.

As for bed leveling… A lot of people think the paper test is all you need, but really that only gets you close enough to start leveling the bed. First thing is to tighten all the springs to within 1 turn of being closed, then adjust the Z switch so that the head homes to roughly that same height. After that you use the paper method to get the bed roughly level, then move on to live testing with a 5-point bed-leveling test print to dial it in. Ideally you want the nozzle gap to be about 75% of the nozzle size, so for a 0.20mm tip you would want a 0.15mm gap to get your print to stick.

As I mentioned to someone else, Creality’s QC is garbage. My first glass bed had better adhesion than PEI and worked beautifully for a few years until the coating wore out. My second glass bed was trash, I never could get anything to stick to it without using hairspray, and now it sits in its box. I have a PEI bed now, which seems to have solved the problem. If you decide to try using the printer again, don’t forget to clean the glass with 90% ISO. Worst case try flipping the glass over to the smooth side, clean it with ISO, then use glue sticks on that surface (you won’t get any adhesion on bare glass without the glue or hairspray).

People give the Ender 3 a bad rap all the time, but it’s honestly a great little machine. I far prefer it to the $2500 printer we have at work that has “automatic everything” and can’t easily be adjusted to manually correct its bad settings.

With that said, how far have you gotten with it? Do you have any software installed? Have you tried printing anything (and was it successful)? You didn’t give much clue as to where you’re stuck. Yes you need to take some time to learn how to fine-tune the settings, and yes it can be frustrating because there is SO MUCH to learn about 3D printing, but once you get over the hump you can start cranking out all kinds of fun things.

To answer your first question, ALL of the mirrors are safe. The idea with mirrors is that you choose one that is geographically close to your location (same country, maybe the same region or state) to help reduce lag in downloading the files. Any selection is valid, all of the mirrors will have the same content, but for your location some mirrors may simply be faster or slower than others.

One other thing you might run in to is different types of installers. Some may be a very minimal install which only give you a command line, while others will provide a fully configured desktop. You might also see an option for a “Live” version – that is something you put on a bootable memory stick and you can test out a working version of the operating system without actually changing anything on your computer, but all of your settings will go away when you reboot.

I haven’t used Mint so I can’t provide specific info, however some things that are common to ANY linux desktop – You probably want to start with printer drivers (install CUPS) and some office software (install LibreOffice). For internet access, Firefox and Thunderbird are good choices. LicreOffice, Firefox, and Thunderbird can all also be used on Windows if you want to check them out ahead of time. There are many lists online that can point you to equivalent software, so like if you use Lightroom on windows, you might try Darkroom on linux. basically you just need to make a list of what Windows software you use and then install a similar package in linux.

Yes you will need some time to learn the new operating system and all the new software, very little will be 100% exactly the same, but they are “close enough”. You figured out how to use all these things once before, so you can do it again, and it will definitely be worth the effort.