How long have you had the printer? The PEI issue might be under warranty. I’ve only seen PEI relax to a flat state when left removed from the bed for a few days. If its not covered under warranty, you’ll probably need a new sheet… if you’re careful and the adhesive is in good shape (flat), the new PEI sheet can be stuck onto the existing adhesive without removal. That can be debated, but removing the adhesive is difficult.
The swelling of filament is called heat creep. Its fairly normal. Make sure the heatsink fan is working and on whenever the machine is on. It doesn’t look so bad in your picture.
To fix the extrusion stopping mid print, you can try a few things.
- Tighten the idler by 1 or 2 turns so that the filament is gripped better by the hobbed bolt. The idler spring should be compressed to about 8mm. There’s also a jig that can be printed to obtain the proper idler distance.
- Increase the extrusion temp by 1-5C. This will help ensure the hotend keeps up with extrusion demand. Just remember to stay within the manufacturer temp recommendations.
Hope that helps.