Toner that smears or wipes off indicates the fuser is not bonding toner to the page. It is time to replace the fuser unit.
Closed-loop heating with an integrated thermistor keeps the fuser surface within the target temperature band for clean toner adhesion. Fast warm-up and recovery minimize swings that cause 50.x fuser errors, toner offset, and wrinkling during long runs.
When to replace the fuser unit? Smudge Reliable Performance Reliable fusing at rated duty (220k)