In order that sensitive structures of inkjet printing mechanisms be cleaned without damaging these structures, a cleaning sheet and a process of using the sheet has been created. Candidate SFDs in an incoming signal are identified using a lower-than-normal detection threshold, and corresponding markers are stored in a buffer. A heater coil is mounted behind the evaporator coil to selectively heat the air moving through the passage. The first ion-removing unit serves to remove a first ion, such anions, contained in the fluid. The shank is biased into the resting position by spring force, which is provided by a spring disk axially supported by the bearing part and having an outer circumference contacting an inside contact surface area of the base surrounding the bearing part. This maintains tension in the wirecloths after cooling.