Manuals - Busy Bee Tools
When the motor spins freely without the belt attached, the sound goes away. The first unloaded run is how the saw should sound, even when it's loaded. The frequency of the "rattle" seems a little hh for a single nick, but if there are a few in a row, I could see that being the problem.
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When the belt is attached to the motor, it makes a sound that seems like something is unbalanced.
Table saw instruction manual -
My first guess would be the saw arbor, since it's not rotating when the belt is off.
I've just put my used Powermatic 64 Artisan's Saw together.
Grizzly tsc-10 table saw manual:
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