Dremel 395 Variable Speed Multipro Rotary Tool Kit "seized motor" Questions

Dremel MultiPro Model 395 was used to cut out drywall, now it does not run.Could dust in the motor be the problem? Tried blowing out the dust from the housing. Drywall dust has ruined your tool. It ...

...motor brush on dremel. One brush is stuck. Tried to pry but the brush tip is still in the spring. Nothing to pry on. Any ideas? Tried tapping the tool, no help. Should I try some WD40? I had to ...