A fuser failure usually shows up as poor adhesion, offsetting, wrinkles or a repeating mark on the page. The decision is whether to replace the complete fuser unit or rebuild it with a new fixing film.
Replace the complete unit when
The pressure roller is damaged, the bearings are noisy, the thermistor readings are unstable or the housing is deformed. These faults are not solved by a new film.
Rebuild with a new film when
The film is worn or scratched but the pressure roller and frame are in good condition. A film replacement costs a fraction of a complete assembly and is the usual choice for high volume service fleets.
Part numbers to watch
Canon imagePRESS and iR Advance machines use several interchangeable fixing assemblies. Always cross reference the OEM number on the old unit before ordering, because the same assembly is often listed under two different numbers.