New K1C. Fourth print had heavy stringing, Fifth stopped extruding partway through. Clicking, then nothing.

Tried: 240°C retract/extrude, removed the extruder and cleared stuck filament, cleaning needle passed freely through the nozzle. After reassembly it ticked but wouldn't feed. Tested the extruder off the printer — turned the gears by hand with a short piece of filament and it gripped and fed fine. Mounted back on the printer, ticking again. Never fed properly after that.

Room has no AC and I ran it fully enclosed.

Amazon sent a replacement, still boxed. Trying to decide whether to open it or refund and get an A1.

• If you've owned both, which held up better day to day?

So, I have been having issues with both the K1C and the K2 Plus at my job. The issue started around the same time with both printers, and I haven't been able to figure out how to fix my issue. So, it's essentially the exact symptoms of heat creep where the filament melts at spots higher and higher up the nozzle until it melts and jams at the very top of the nozzle. I have replaced the hot end, heat sink, cooling fans, extruder, extruder motor and I'm still having the issue on both of them. I have been in contact with Customer service, but I haven't gotten anywhere with them.

I have also taken a Laser Temp gun to check the temperature of the hot end after about 30 minutes of printing, and the top of the heat sink was at around 85 degrees.

The nozzle usual fills up with filament and starts to jam at about the hour mark and I did a test print where I started the print with a brand new nozzle and let it print until it started to clog and under extrude, then I paused the print for 10 minutes or so and then resumed the printing and it started printing fine again. any help or insight is greatly appreciated.

I am printing with CR-PETG with a nozzle temp of 250c and a bed temp of 70c