Why doesn't my Dremel 300 won't spin?

Your brushes in the motor are shot. Or the drill got wet and the bearings are seizing up.

The problem could be with the switch that powers the motor or the brushes on the motor itself may be worn. Also look for bad connection in the wiring.

My motor was turning but the flex shaft wouldn't. I took the flex shaft loose and spun it inside. Works fine now.

If it makes noise but moves, it's your motor - it it doesn't move at all, it's the belt. Noise and won't move, get a new washer. Check the BELT first - that usually is the problem.

How could the belt be in working order if the drum doesn't spin? Check to see if the belt has come off the motor. If the motor runs but your dryer doesn't spin, the belt is off. If the motor runs with the belt on but it still won't spin then you'll have a lot of black smoke because your drum is jammed. In other words, there are a number of things that could be wrong, but not very many.

The noise you hear is probably the belt slipping. Turn the A/C switch on and look at the compressor under the hood. the part of the pully on the front side of the belt should spin, stop periodically and then start spinning again. It's tough to tell from here but the odds are that the belt may need to be changed and the system charged with Freon. When the freon level gets too low , the system won't start up and cool the car.


Best wishes.

My dremel started doing that too. If I rubbed the sanding drum along a piece of wood, it would start up again. I think the brushes and the copper armature get glazed over with non conductive dust and possibly insulation smoke which disconnects it enough to stall out. Change the brushes to the new ones in the kit. After a year of heavy use mine slowwed down to about 300 rpm and then died. A very nice tool but I prefer the Makita which is about three times this size just because it is longer lived.

It is with regret that I must inform you that you will probably have to replace the whole unit, the field coils will have blown and almost certainly the armature - your did give it a 100% over voltage shock. The prices of the parts will be more than the cost of a new machine.

The "nub" on the shaft lock assembly (internal) has worn down and the assembly needs to be replaced.

If you feel competent to open your Dremel yourself (and it's not on warranty) then order the shaft lock assembly from Dremel (early 2011 price: $1.25, not sure how much postage & handling might be). After opening the tool you will find a metal ring and a small piece (the lock) which it holds in place around the shaft where the lock button is located. Remove the old pieces and replace with the new ones and reassemble the tool.

Otherwise you can send the tool to Dremel to be fixed.

Trying to fix a similar issue. The pin that gets pushed in by the button (and returned by the spring) seems to be fine. The hole in the rotating shaft that the pin fits into, however, is in the wrong place, so the pin never goes into the hole! All I need to do is somehow pull the whole front part of the shaft out about 1/16th of an inch, and it'd be fine. I just can't seem to budge it though. Any tricks, anyone?