@jfahner, @zimmer62, @James_the_sparky and other 3D printer experts:
Where do people recommend getting spare parts for the Prusa i3 MK3? The Prusa site has all the things of course, but says there may be a 2-week lead time. Is there a reputable source other than random eBay sellers?
For background, 2 or 3 weeks ago the print fan was failing because of a loose wire in the bundle. I replaced the wire and kept going. Now I’m getting an intermittent thermistor problem, which I think is also a loose wire. It should be fixable, but I want to have some spares on hand for when it’s not.
I want to get 2 each of the fans, thermistors, a new steel sheet (which is in stock a Prusa), and I guess nozzles. What am I overlooking?
This printer has been a champ. I’ve printed 275 face shield headbands, running it almost around the clock. When this is all over and it goes back to live in the shop, I want to replace these parts so it’s as good as new.
I just faced the same question. I just put in an order with prusa to have a full spare hotend.
The textured sheet is awesome for petg. It sticks well and comes off super easy.
Spare steel sheets are cool, did you know you can get new pei stickers also. Then you just fix the surface of the plate. Might be worth getting a new sheet and a pei.
The Prusa website says “Spare parts purchase is limited to Original Prusa 3D printer owners only” for most of their parts. I’ll buy from Amazon or somewhere else, I guess.
I would just order them from Prusa. It may take awhile, but you will know they are right and of high quality.
I have three spare thermisters of the type used in the MakerFarm machines. They may be adaptable so if you need one to continue printing, I could get one to you.
I also have an extra PEI sheet from Prusa that is 260 mm x 225 mm if you need that.
I might take you up on that. I think the thermistor is going bad. The printer halts after 15 - 30 minutes of printing, with “MINTEMP” error. Is your thermistor for an E3D hotend?
No, the thermistors that I have are bare glass beads with the two leads coming out of them. They seem to be 100K ohms. and are not encased like this ED3 one:
I think the one that is in there is held by a setscrew. Older RepRap machines just used a smaller hole with some kapton tape to hold it in. You may be able to find a tube to encase it in or just use something like furnace cement to hold it in.
You have probably seen this video about faulty wiring:
My experience has been that the wiring has been the problem when I got this error.
Let me know if you want to try one of my thermistors.
Oh, too bad. I ordered a replacement from E3D online yesterday. It’ll be here next week, I hope. And I watched that video, too.
It might just be a bad cable, but I guess they can just go bad with age. And I have been pushing it hot and fast for several weeks.
Thanks
The parts came today, and I got the new thermistor installed. Not easy to get the old one out. I took out the grub screw, but I had to use pliers to pull it out.
The new one has a connector near the thermistor, so the next replacement will be easier. I won’t have to unwrap the whole cable bundle.
I got a new nozzle also, but I wasn’t able to unscrew the old one. I heated up to 280C, and held the heater block with a wrench, but I couldn’t loosen the nozzle. I didn’t want to put too much muscle into it and break something, so I just gave up.
But I’m printing again.
I spoke too soon. I woke up to another MINTEMP error. 
