Berson reactors with an automatic wiper sweep the outside of the quartz sleeve on a timed cycle. Scale, iron and organic film on the sleeve attenuate UV-C before it ever reaches the water, so a stalled wiper shows up as falling measured intensity on lamps that are themselves still good — and is a common cause of a reactor being taken off duty for a lamp problem it does not have. This is the complete wiper motor module for the InLine range, supplied as an assembly rather than as a bare motor. Confirm the reactor model and the existing motor designation before ordering: the InLine range has used more than one drive across its build standards.