Dremel failure - need some repair advice

[Rollerball]

I have a Dremel 300, one of these:

http://images.dremeleurope.com/gb/en/ocs/image/ocsjpg--/dremel®300series-9657.jpg

I've had it for a few years and use it occasionally.

This afternoon I used mine to grind down some plastic, it was working fine. I finished the job, went to use it again and it then wasn't spinning as fast as it should and sounded very "crunchy".

It then stopped spinning altogether and now just buzzes when I power it on and the motor gets rather hot.

The spindle turns okay if I spin it manually (in fact, when the fault first started I could get it to spin up by briefly spinning it manually, but that doesn't work any more). There's no sign of obstruction.

Brushes look fine, have taken it apart a few times and can find nothing obvious wrong. Bearings are fine too.

Any ideas please ?

 

[Burnerman]

I'm afraid it sounds like the armature has gone AWOL, unfortunately - the odd noise being excessive sparking at the brushes. I guess the motor wouldn't reach full RPM?
John

 

[Rollerball]

That's a pity, the cost of a new armature means that it would be more cost effective to buy a new Dremel (probably the 3000 as they're only a little over 30 quid on Ebay).

As you say, the motor (when the fault started) wouldn't reach full RPM (and when it did spin it sound very rough).

Thanks for your help - I was hoping that it would be a cheap and easy fix.