swamp cooler motor problem

I am having a problem with my swamp cooler. Just this season, when the fan is on "high" (I only have 2 settings), it will all of the sudden slow down to low (for 5-30 seconds) and then speed back up again
to high. This has never happened before and I have lived in the house for 3 summers. I do the maintenance myself, but I didn't notice anything untoward when I was setting up the cooler this spring. It sounds like it might be the motor and/or bearings? But how do I find out? And is it easy to replace the motor? Thanks!!
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Your motor might be drawing too many amperes, but those motors usually just die for awhile, 'til the overload circuit cools. If there's an adjustable pulley on the motor shaft, try to open it up a little. If this is beyond your ken, go to a hardware store to look at an adjustable pully. It's got a setscrew that needs to be loosened to turn the outer bevel of the pulley on its threads, then retightened. Piece of cake to replace a motor if necessary. You might need a gear puller to re-use the pulley from the old motor. Love the word "untoward". Tom bearmd wrote:

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Are you sure it not the belt slipping?
Al
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How would I know if that's it?
Big Al wrote:

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