speed variation

[Dave]

My Porter Cable 333 has been good until recently. Now the speed seems to vary. It slows down, then surges What would cause that??

[Mark]

Hi Dave,

There are two likely causes. First, the clutch belt, item #37, may have broken. I have seen this belt break and then roll itself up into a ball between the pad and the underside of the sander. Basically acting like a brake.

The second item would be a bad pad bearing, item #11A. A bad bearing will put a great amount of load on your sander and cause it to slow down and act erratic.

I hope this helps!

-Mark