Travis7s

Have you tried turning it off and on again?

But be careful! Once you start using a Wera driver you'll start to wonder why your other screwdrivers aren't Wera too. Next thing you know you're spending hundreds on Wera, Wiha, and Knipex tools.

Did the printhead stop moving or is it moving around but nothing is coming out? Never hurts to clean but the S5 *should* be giving you a material error if there's a significant nozzle clog. (although I think you can turn that off in the settings)

I too have had intermittent issues with PLA/PETG/Nylon. I'd say 90% of the errors are "false" in that you can just hit resume and literally do nothing and the printer will happily finish with no quality issues. I have never really adjusted the tension. I know some veterans like @gr5 recommend oiling the bowden tubs with great success.

I would try running it through a UPS, might solve it if its a power grid/noise related issue. My S5 worked great for years in the exact same location and then just randomly started stopping and melting its head into the print. Once I used a UPS it all stopped and I tend to believe the nearby HVAC equipment was causing it to brownout or something. Also check your limit switches. My Y switch arm was bent a few mm and it causes my S5 to behave very erratically including crashing into things.

Colliding is not normal although on my S5 the clearance is surprisingly tight. If it seems to print fine otherwise, I think the simplest solution is to try to add a small shim/spacer under the switch bay bracket? Its just held on by 1 screw through the side panel so very easy to remove.

Its called a terminal block, I don't know the exact replacement but you need a 3 (or 2) position one and approx 5mm pitch spacing. I would guess that the wire was loose in there and so it was arcing heavily while the bed was heating up (high current draw) so make sure you really tighten everything good when you replace it.

It seems very odd that this would happen to two print cores back to back, not sure what could specifically cause this. Are you sure the nozzle isn't accidentally crashing into the edge of the plate or something weird like that? Example: if the rear metal clips that hold the glass are bent up the nozzle can run into them. I did have this happen to one of my cores where the nozzle cracked and filament was leaking out the crack while it printed. I assume it was just from wear and tear (heat stress, damage from crashes). If none of the wires are ripped out and the filament can still flow, the printer has no way of knowing anything is wrong.

https://support.ultimaker.com/s/article/1667417573978 Although I would say there isn't enough excessive material there to cause issues, it usually takes a big blob right under the nozzle for me. Depending on what error type you are getting there are more troubleshooting pages here: https://support.ultimaker.com/s/article/1667410781005

+1 for checking the side fans, debris like a loose chunk of support structure can get in there and jam them up. The printers can't report if the fans are actually running properly so you need to visually check.

I used to get just a black screen for the camera and would fix it by "Cure Conect Reset" in the maintenance menu although I don't recall ever not seeing the blue camera icon.

Personally I think skirt is a much nicer way to prime than a blob or extruding in space. Less "mess" inside the printer enclosure and blob especially becomes a liability because it can get dragged by the nozzle or sometimes people forget to remove the blob and you start getting blobs on top of blobs.

Since no replies here, which is more of a end user community, probably best to open a help ticket from the official Ultimaker website. The support team there is pretty good.

Just as an anecdote, my S5 was randomly failing and just saying "Print Failed" for seemingly no reason. But we eventually thought that the large air conditioner units would kick in and occasionally cause a power brown out that wasn't noticeable but caused the printer to reset. We added a UPS to the printer and never had the problem again.

Click on Preferences >Configure Cura>Printers>Machine Settings