My oldest P1S can no longer successfully print PLA. It consistently partially clogs and the print ends up super fragile where it missed extruding. What’s bizarre is that I can cancel a failed PLA print, change nothing, and retry it in PETG and the print will come out perfect. PLA = Clog, PETG/ABS = fine.
Things I have tried:
Replacing the yellow extruder gear
Replacing the nozzle
Replacing the heating component of the nozzle
Replacing the thermistor
Re-applying thermal paste
Super cleaning the gear with a toothbrush and IPA (this did help for a week or two, but it’s not dirty and failing again now)
Increasing filament temps for this printer only
Lowering bed temps and opening door
The model it most recently happened with is fairly thin, but it doesn’t seem to matter. Prints I’ve done hundreds of times on this printer are now impossible. I don’t want to mark this printer as PETG+ only…
Have you tried increasing the nozzle temperature to an extreme level? More importantly, if you say PETG/ABS prints okay, did you try printing using the PETG profile?
I’m willing to wager your nozzle temps aren’t high enough. Even though you’ve performed the usual maintenance checks and replaced hardware associated with temp issues—such as a faulty nozzle and thermistor—it wouldn’t be the first time someone reported a similar problem, tried a hardware remedy, but overlooked extreme slicer settings. So, if your filament temp was set to 220°C, bump it up to 250°C, 260°C, or even 270°C to see what impact it has on the print. It might look bad, but that’s fine for diagnostic purposes. If higher temps work, then you may want to revisit the entire temp probe chain starting with replacement of the thermistor but reapplying a fresh amount of thermal grease in to the hole after it was properly cleaned.
A more extreme diagnostic step is performing a manual check of the nozzle temps. This involves invasive techniques like placing a thermocouple under the silicone sock. It’s likely overkill in your case but can provide insights you can’t get via the control panel. You’re looking for significant departures between the temp reported by the controller board and the thermistor—they should be within 5–10°C.
Here’s some equipment I keep on hand for this purpose. I usually use it for diagnosing GPU or motherboard issues, but it works just as well with nozzle heads. You’ll need to jury-rig a system to secure the thermocouple cables during testing—Kapton tape works well. In fact, securing the thermocouple with Kapton tape can work without using thermal grease, but it’s up to you how much effort you want to put in.
Here’s what I use.
Photo in case this goes out of stock. There aren’t too many of these on Amazon.
Any cheap thermal grease will do. Take it from a systems builder, thermal grease is overthought and the differences are major increase in cost versus only 1degree difference in efficiency, for diagnostic purposes anything that is thermally conductive will work, test on YouTube in fact that even peanut butter has been shown to be an effective thermal conductor for short periods of time so don’t get hung up on what kind of grease you buy. https://www.amazon.com/s?k=thermal+grease
Do a calibration… Buuuut, your Z screws go up to a holder, inside that holder there’s a plastic looking insert, if you grab the z screw and try to move it back and forth, do you see sponginess at that top insert? (allowing Z to be terribly inaccurate when it happens) PETG doesn’t need Z accuracy, it sticks.
