: The master-on-drum sensor is dirty or blocked by ink/dust, leading it to signal that a master is present when it isn't.
If the velvet is dusty, worn, or scrunched up, the sensor sees a reflection from the metal/mesh underneath and thinks a master is present.
Are you using a on this drum, or did the error start after a specific incident like a master jam?
: The master-on-drum sensor is dirty or blocked by ink/dust, leading it to signal that a master is present when it isn't.
If the velvet is dusty, worn, or scrunched up, the sensor sees a reflection from the metal/mesh underneath and thinks a master is present. riso error a16-525
Are you using a on this drum, or did the error start after a specific incident like a master jam? : The master-on-drum sensor is dirty or blocked