H2D multicolor prints no longer coming out clean. NEED HELP! 😭

[humble sage]

I have been printing these small face pieces for a while now with no issues. But at some point, they stopped coming out clean! I have tried a ton of trouble shooting: I replaced the nozzle blocker, opened a brand new thing of freshly dried in the AMS Petg HF, I have lubricated everything, nothing seems to fix it. This is especially frustrating because as I mentioned, I’ve never had this problem in the past and I have not changed anything I’ve been doing. So I don’t know why I am randomly getting this issue now. And it’s not one bad batch. Every single batch I have printed from a certain point has ended up looking like this.

Here is an example of the face pieces that used to come out looking good:

Someone suggested that it may be the nozzle blocker not working, so I tried printing a small batch only using one nozzle. And it actually turned out looking OK:

This is another batch I printed using only one nozzle. The pieces looked better, but still too many defects. And I don’t really want to be printing with just one nozzle anyway.

[limber hatch]

Since you already mentioned drying the filament, could you maybe try watching your printer print one, and try to pinpoint at what step in the print it does this stringing? Might help narrow things down a bit.
If it's not wet filament, it's odd that it would suddenly start if you haven't changed any settings.
What I can also recommend - do a cold pull. Sometimes gunk gets in the nozzles and can cause uneven extrusion - which can cause issues like this, sometimes.

[humble sage]

I have watched it a few times, trying to pin down the issue. But without much luck. Best I can tell it is probably is some kind of stringing or extrusion issue. I should mention that I even put brand new nozzles on it. And it did not seem to help at all.

Here is the difference between a old prime tower from a successful face print, and a current prime tower from the defected face print.

[limber hatch]

Have you done a retraction test? It should help you find a point where you can minimize stringing, at least, though if it was printing fine before with the same settings I doubt it will completely solve the problem.

Reading your original message again, it does seem like maybe I misread the bit about drying the filament. You said you replaced the desiccant, I guess? Drying takes time and requires heat for most effectiveness.

I'm guessing you've got an AMS 2? I believe that one does have a drying function but it might be worth double-checking to see if you're actually drying your filament. Drying during printing helps but only if the filament is already dry.

[humble sage]

Yes, I dried the filament for 12 hours in the AMS pro.

[limber hatch]

Hrm. Very weird, then. Retraction test time then?

[trail zodiac]

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[humble sage]

I’m starting to suspect that there is something wrong with my right tool head. The faces on the left were printed with black in the right nozzle and white in the left nozzle. For the faces on the right, I switched the black and white.

I really don’t think it’s the hot end, because these are both brand new. And you can see the ones on the right have white stringing and the ones on the left have black color smearing.

These are 2 back to back prints. The only difference is I switch the black and white.

I also want to reemphasize that I have never had issues in the past printing these faces. So I feel like something must’ve changed with my printer.

[real steppe]

• Is there a new nozzle on the right tool head?
• Can you tune retraction + flow for each toolhead independently?
• seam locations?
• something loose (e.g. screw) in the right toolhead?