20 Most Recent Dremel & Stylus Lithium Ion Cordless Rotary Tool - Page 3 Questions & Answers

Black is positive(+) and white negative(-).
Circuit board should be marked.

It's possible that the enameled copper coiling on the stator was compromised when it overheated creating a short. Sadly, unless you have a replacement stator is cannot be fixed. Sorry.

3 in 1 is a light oil used the lubricate small joints, plates and bearings. It can also be used as a releasing oil for stuck bolt etc. 3 in 1 is usually ok to use in small amounts to grease the bearing points on your Dremel.

You can use canned air for light dirt,or compressor with blow gun for heavier dirt.

I don't know if it has a fuse - I know little about the Dremel brand but I have had some experience of similar other brand tools. The electronics seem less than completely reliable being physically too small for the job of speed regulation, torque compensation, radio interference suppression, etc. - everything is crammed into a tiny space and the circuit board is typically on the cheap and nasty side. If there is a fuse it would typically be found on the circuit board. Mostly the failure of such tools, in my experience, is caused by the electronics though nothing can be ruled out. I suggest you check the mains cord using a multimeter and then check the motor and if both are OK it is fairly safe to assume the fault is circuit board related.

No.. the issue issue is the switch inside. when your Dremel 4200 stop working, press firmly the grey area between the speed selector and the brush housing. I think this a defect in the design of the 4200.

The Dremel 200 has two speed control which allows you to set your speed at 15,000 or 35,000 rpm with a flip of a switch

check for a broken / damaged drive cable

Yes it does. If you have any questions call Dremel hot line. They're sharp. More details Complete Dremel Workstation 220 Review

Overheated motor, bad power wire or bad switch

they're caps on the brushes for the motor

You can order one through dremel.com or ebay. I happen to have one as well. Harbor frieght has roto tools for around twenty bucks that will fit dremel tools as well.