Fe-6 waterfall not working

I have a Cavalier FE-6 wet cooler. It has a circulator motor in a stainless steel housing that creates a very pretty semi-circular waterfall which circulates the cold water above the water line.

Recently the water stopped circulating with enough force to create the waterfall. The motor seems to be running fine and the impeller shaft spins freely inside the cooling coils.

I removed the housing and was able to disassemble the impeller shaft. The impeller shaft connects to the circulator motor by way of a rubber coupling. At the bottom end of the impeller shaft is a three blade fan. The fan is attached to the shaft by a very corroded knurled nut. The nut rides on a bearing on the floor of the unit.

I suspect that the corrosion is slowing down the rotation of the impeller and preventing it from generating enough speed to lift the water properly. I am afraid to try to remove the corroded nut in case I cannot replace it. I am attaching a photo of the impeller shaft and the bearing that it rides on.

Has anyone else had this problem? I'd appreciate any suggestions.

Thanks very much

[johnieG]

Hmmm,  '>    are you sure theres no blockage in the waters return trough in the floor of the cooler? or possibly the strainer's plugged up preventing the water from recirculating? (lack of return flow) lift up the channel in the floor & inspect the water's return path first...that's my suggestion

Thanks Johnie.

I don't think the return flow is the problem. The trough and the strainer are clean. No hint of any blockages there.

I appreciate the suggestion though. Any other ideas?

[johnieG]

Well, here's one is the shaft maybe "slipping" in the coupling?
or  the motor's bearing  is dragging the shafts spped down, if it's a three wire motor (the motor uses a split-phase capacitor to run) the "cap" could be drying up & effecting the motor,s run speed too, hope these ideas help you out.