I make it a habit to maintain the PEI sheet using a soap solution and a dishwashing sponge, and I periodically check the bed leveling mesh (there are instructions for this in the Sparkx thread). I also lubricate the moving parts: the trapezoidal lead screws, the print head linear rails, and the heated bed rails. Before a long print job, I remove the old lubricant with wet wipes—they are excellent at cleaning off residue—then apply fresh lubricant and wipe away the excess. The best way to apply lubricant to the screws is with a standard paintbrush, while tweezers and wet wipes work well for removal; for the linear rails, it is quite convenient to simply squeeze the lubricant directly from the tube. I have tried using various applicator tools, but they proved ineffective; simpler is better.