Help--Table Saw motor changes speed !

I have a question about my table saw. It is a 10" Rockwell table saw that is about 30+ years old. Lately when I run it the motor has been coming up to speed but then slowing down and speeding up on its own (without a load). I checked the brushes and they look OK. Any idea what could be causing this or how to fix it?
Woody
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supplied with a repulsion-induction motoe. If it has a universal motor, it is rather old to have the original one.
In the case of the repulsion-induction motor, a failing centrifugal switch would cause this problem. There may be other reasons as well.
If you have a universal motor, I don't know. The no load speed of these things is usually limited by friction in the bearings. Perhaps the bearings need replacement. There may be other reasons as well.
I would take it to an electric motor repair place. Those guys see more bad motors in a week than we do in our entire life.
Jim
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It has the original motor. I don't know what type it is, just that it is not a separate motor, but instead is integrated into the arbor that turns the blade (via a very short 6" belt). Today I disassembled the saw, removed the blade and turned it over (table down) and ran the motor for awhile. At first it varied speed as before, but after a few minutes it started running at constant speed. I guess tomorrow I'll turn it back over and see if it still runs constant or varies again.
Woody

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same mechanism used in circular saws.
You could take it apart and lubricate the bearings.
Jim
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I greased up the transmission and noticed that a lot of the grease was coming out of the joints, so I checked all of the bolts and found many of them loose from years of vibration. I guess that was also preventing the grease from being fully distributed inside, and once I tightened the bolts and re-greased, the problem was fixed.
Thanks for your suggestions, Jim.
Woody

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