Kobra S1 starts printing, then stops extruding and keeps air-printing - any ideas?
I picked up a used/customer-return Kobra S1 cheap on eBay and I’m trying to work out what’s actually wrong with it.
When it first arrived it immediately threw error 11407. I followed Anycubic’s troubleshooting guide and found the 10-pin cable harness was loose. Reseated it and the printer then booted normally.
Since then I’ve:
Connected it to Wi-Fi/app
Run the full calibration successfully
Cleaned/flipped the PEI plate
Tried the built-in Benchy
Confirmed it purges/“poops” filament normally before printing
The Benchy starts printing and actually lays down the first part fine, but after a short while filament stops coming out completely while the printer carries on moving as if it’s still printing.
I’ve attached photos of the failed print and the nozzle area.
The hotend doesn’t look obviously blocked or covered in a blob. I’m wondering if this is:
extruder tension / the lever position
filament slipping in the gears
partial hotend clog
heat creep
something else common on the S1
Has anyone had this exact issue where it prints normally for a bit and then suddenly starts air-printing?
Any suggestions on what you’d check next would be appreciated.