Note: Be very careful with your heatbed glass while replacing the PEI, it is borosilicate glass and very prone to chips and breakage if improperly handled.
Using a razor blade, peel up a corner of the damaged PEI and pull the PEI sheet off.
Spray the glass with Rapid Remover. Apply a generous amount. Ensure the rapid remover doesn't make contact with the heat pad adhesive.
Using a scraper, scrape adhesive into a pile on the glass. Re-apply adhesive remover as necessary. Remove adhesive from glass. Repeat until adhesive is no longer on glass bed.
Inspect glass for chips, scratches or cracks. Clean glass with Acetone. Wipe down with a lint free towel.
Secure the cables by wrapping the red thermistor wires around the white heater wires.
Locate and use the peg board jig. Lay the heat bed so the heat pad is against the peg board and the cables are sitting in the cut out.
Run the heat bed and peg board half way through the roller. and set the roller pressure to 100% and 2mm on the digital display.
Remove the bed and peg board form the rollers. Spray the glass with 3M glass and wipe down with a fresh lint free towel. Check for streaks. Repeat if necessary.
Lay the adhesive side of the new PEI against the edge closest to the roller. Feed the peg board and the bed into the roller, place hand on bed to prevent the bed from sliding. Remove hand from bed when the rollers grab the bed. Keep the PEI at a 45 degree angle and slowly peel off the backing.
Remove heat bed from rollers.
Inspect cutting board for debris.
Lay rolled heat bed PEI side down on the cutting board. Score the PEI along the glass on all edges with excess PEI. Bend open the cut and snap off the excess PEI.
Run a blue shop towel along the edges of the PEI to prevent any loose material from scratching the PEI.
Place bed PEI side down of the butcher paper for final “soft press”. Set roller pressure to 60%. Keep the connectors on the outside of the rollers as to not damage the rollers (left side of roller). Run the bed through.
Post bake bed for 1 hour at 115C
After the bake while the bed is still warm, put the bed through the rollers the same way as in step 2, except the PEI is already applied.