1: Shadow\doubled line visible during cuts
2: Unusually heavy buildup of soot around air nozzle tip
3: Z-height only moves in set distances (approx 1 cm) per button push
instead of the normal movement only when the button is actively pressed.
shadow: loose lens
soot: deep blasting of material out of a board, or cutting cheap plywood
z-height: It appears that someone made adjustments to the default settings(can’t lock people out.)