If I may say, if you’re looking for troubleshooting help, you need to slow down and address one item at a time. One thing is certain: performing a factory reset does nothing for filament and model settings. It only resets the printer’s internal configuration, affecting memory and network connectivity, nothing else. If a factory reset is affecting your output, it’s an indication that something is corrupted in the way the model is being sliced or uploaded to the printer.
Let’s first focus on what’s happening and get some facts:
- Are you using an AMS? This hasn’t been confirmed in your previous posts.
- When changing filaments, do you run a small test print, such as a 2mm high cylinder or cube, to ensure you have a completely clear filament path?
If I had to guess, your settings are getting corrupted or reverting to a different filament profile. This happens to me when I’m not careful with loaded settings. In Bambu Studio, changing printer profiles can cause it to switch to an unrelated filament profile. I once had PETG loaded, but the profile reverted to PLA when I changed the printer profile, which was frustrating. 
Troubleshooting Recommendations
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Try closing Bambu Studio and reopening it after filament swaps. This is a less invasive debugging step than performing a factory reset and ensures that the project settings are always reset to the correct values. While it shouldn’t be necessary, it’s a diagnostic measure that may help.
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With TPU, after filament swaps, I find it helpful to print a small test object. I usually print a 25.4x25.4x2mm cylinder primitive, which ensures a total purge of the filament path. If you’ve ever tried this with two contrasting filament colors, you’d be surprised at the amount of junk left in the nozzle that the purge didn’t expunge. Try this step to confirm your filament is fully purged between changes.
Disclaimer: I hate TPU—it’s the devil’s spawn of filament
. But it’s necessary for certain prints, so I’ve learned to “tame” it, not “master” it.
Tips with TPU
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If you think your TPU filament is dry, you’re probably wrong
. Dry it again. Even a 0.03% moisture content can be the difference between “stringy” and “gappy.” Always dry the filament before using it. -
Turn on the setting “Avoid Crossing Walls.” While it might not make a difference in your example model, it can really help.
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When dealing with a tricky model, a good fallback is to run in silent mode, which reduces all nozzle movements by 50%. If you’re motivated, you can manually adjust the speed settings to find the ideal flow rate, but silent mode offers an easy one-click option that cuts speed by 50% (though it doubles print time). The difference in print quality is significant.
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Experiment with layer heights. A finer layer height like 0.08mm can help with some models. I’ve found that keeping the layer height below 0.24mm works best for most TPU prints. The photo above as an example, the one on the right was at 0.28 and the one on the left 0.08 at 50% speed. It was still string as hell but it got the job done.
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Did I mention drying the filament?
