Subscribing... I burnt mine up yesterday. I let it cool for the night. Hopefully it will start again today. If not I'll be trying some of the tricks in this thread. 

I swapped the fuse for a 1 amp fuse.. Too low to fry the dremel but high enough to let it work.. I was popping them and fried my old dremels but oddly since I swapped to 1amp I have been lucky and not fried it yet.. although the speed control does not work.. lol... I used to wrap the body with some breather cloth.. it worked OK.. 

Oh by the way... The original fuse was 3 amp... I wanted it to blow the fuse before it could do anything to the motor.... I am not increasing the rating of the fuse.. NOT A GOOD IDEA...

Well here is an update. My Dremel is now toast. Carbon dust is highly conductive and shorts things out. I bought a new Dremel  and the long flexible shaft and everything seems fine now.
Fred

I know this is a very old topic, but just thought I'd post seeing as I was reading through...

Ive rigged up a separate inlet pipe and fan to cool the motor out that sucks in air from a safe area away from dust, the silicone is there purely to stop the dust after its been sucked up disappearing though panel gaps before it gets to the collection point. 

mmm probably you should remove the silicone from the gaps ASAP because the motor of the vac cleaner needs to breath....you can you a piece of cloth instead, which will block the dust but not the air

A compressor and air tools are not really expensive compared to conventional mains dremel and alot safer! Just just require slight oiling thought the air inlet pipe daily and the should last a long time! So much safer as they wont short out too. I always has a vacuum cleaner as close to the blade as i can sucking in the dust, but i cant seem to find a vaccum cleaner that is none electrical so i have just sealed all the gaps up with silicone.  

I'd also suggest to blow out the dust but keeping in mind that you have to remove the dust away from the dremel by keeping the line a bit further and away from the vents. If you blow the dust without care you might push the dust further inside the motor which will make thing worse.

Probably a good idea to blow out your dremel with compressed air every once in a while.

Fred

I use a dremel and a saw fein. I always use vacuum cleaner near the blade