Weird sagging / drooping problem on production files


I’ve been using M200’s for more than 5 years now. I have 3x of M200’s at the moment printing mostly 24/7. I’ve had ton of experience of fixing these machines but this time I’m running out of ideas.

We are running Z-Code files that we’ve been using for more than a year now flawlessly but suddenly the oldest of my M200 with 11.5k printing hours started randomly giving me weird quality issues - plastic sagging over even tiny bridges and overhangs. Here are a few pictures with how the parts look like normally and how they look on this machine now (there was no gradual appearance of this issue, I just noticed from one point having these issues and it’s been like that since):

Since there are no other visual issues like under extrusion or brittle parts the only logical thing that seemed to cause this was either:

  1. Not enough cooling (I had swapped my cooling fan to a Noctua one on this printer without any noticeable effect and it is working just fine so it’s hard to see how this could be a sudden problem)
  2. Heater/Thermistor has gone mad and are giving some wrong readings and overheating the hotend

So to test my theory I removed the Noctua fan and replaced it with a brand new stock one from Zortrax and guess what - nothing changed.

Next up I swapped out the heater/thermistor pair (to be fair, I don’t remember when I swapped it the last time) with a brand new one. Aaaaand… nothing changed.

I also cleaned up the heat brake fan and channels to make sure it’s not overheating there - no visible changes either. Fans spinning just fine.

Next up is a nozzle change (honestly makes 0 sense but there’s not much left to try to swap out). Will report how this goes.


Well… as stupid as it sounds - looks like the nozzle was at fault.

This makes no sense at all but this solved the issue. In my 5+ years of operating M200’s, I never had seen such an issue caused by a nozzle. Lesson learned.


Hi @practicalmike,

I am glad you found a root of the problem. Also, all the suggestions you have provided are correct - there might be a problem with insufficient cooling, malfunctioning heater&thermocouple, PCB, hotend or nozzle. Please note that we recommend replacing the consumable parts regularly (as suggested in our maintenance guide). Thus, if you come across a similar issue again - please note that the whole hotend might require replacement.

Best regards,


Thanks for documenting this for others. I kinda wonder if you had a possible clog or something that would effect the pressure and material flow.Maybe only obvious in less supported areas? Anyway glad to know that worked and you will certainly save me some troubleshooting steps when mine does something similar.

Stay well