2238C says out of cyan toner but there is toner

[Solotime]

I have cleaned out the toner tubes and verified that toner shoots out from under the cyan hopper whenever the "toner pump" runs as it is trying to add toner. I am sure your familiar with the sound they make when they are trying to add toner. So I hear the noise but it just continues to try and add and then shuts down with the Cyan empty indicator.
What am I missing? Also, is the toner pump the part that sits right above the developer unit at the back where toner enters the dv unit or is it somewhere else?
Thanks

[Lagonda]

There are two pumps on this model, the one under the toner hopper is an air pump that blows the toner through but the main one, the "attraction pump" is the one that sits at the back above the dev unit.
The usual problem is the clutch is slipping on the attraction pump. Due to the age of this copier I would replace this pump before worrying about anything else.
Give yourself plenty of time as you usually have to take the gearbox in the back off just to get to the connector for the pump.