Thanks for the post!

A couple of things come to mind...

1. Loose wires connected to the switch or motor.

2. Brushes are worn down or are not touching the commutator on the armature (check to make sure the brush springs are in good shape, which put tension on the armature).

3. Make sure you have continuity throughout the tool. I would take a voltage meter and connect it to the power cord to confirm you're getting a good current.

You can watch a video on how to do just this below:



4. Make sure the armature gear and planetary gears aren't stuck/damaged. To confirm this you'd have to remove the gear cover, of course; I would check this last.

Hopefully this gives you a good starting point.

- MTR

I think there may be a section of the commutator (which the brushes make contact with) that's damaged/burnt or missing completely, causing this problem.

Check to confirm all of the copper sections of the armature's commutator are there; you may need to "dress" the armature to clean it up, and you can buy a product to do this at a hardware store, typically.

Make sure the field and armature windings/wires aren't burnt or missing as well.

- MTR

It's hard to say, then, without having it to diagnose myself.

The problem with this is going to be obtaining parts; I doubt they're available through Northern Tool as it's probably an import saw private labeled.

The gears could be jammed, you may want to remove the gear case and take a look. If all of the electrical components look okay and the armature and brushes do as well, I'd look at the gears.

- MTR