Vacuum motor only runs in spurts

[lucid]

Older Kenmore canister suddenly quit, then restarted for 2 or 3 seconds, stopped for a few seconds...restarted...stopped...etc. The run spurts seemed to grow shorter and the stopped intervals seem to grow longer.

But I didn't leave it on to see what might happen as there was a lot of sparking at the commutator during the running "spurts". I replaced the 19 year-old brushes, but nothing changed.

It's a single stage blower, current Kenmore # is 4368931.

Any ideas?

I should add that the armature spins freely on new bearings installed 4 months ago. At that time, a spacer washer was overlooked and left out. Another one was installed while shooting this problem, to raise commutator a bit for better brush contact.

 

[joecaption]

I'd pull out the comintator again and check for continuaty between the brass contacts. It should have ohms through each and everyone. It not it's shot.
Also try cleaning the comintator with a pencil eraser.
Make sure there's nothig metal stuck between the contacts on the comintator. I use a dental pick to check.

 

[nealtw]

Check out the switch!!

 

[nealtw]

And the cord.

 

[lucid]

Switch and cord are both good suggestions, but I get the same symptoms with the motor removed, and powered by a different cord from a switched power strip.

 

[JoeD]

Brushes on the motor are probably worn out. Was there a lot of fine black powder inside the vacuum?

 

[lucid]

Thanks Joe, but as noted at the top the brushes were replaced, with no change in symptoms.

I bit the bullet yesterday and ordered a new motor from sears direct (PN 4368931).

 

[nealtw]

Is there a chance there is a overheat switch on the motor.

 

[lucid]

That's what it seems like but I don't see anything except armature, field windings, and brushes.

I gave up and ordered a new motor for $82 from Sears, which came yesterday. I'll be putting it in today.

Thanks for your interest, Neal.

Bruce Young in Central NY.