...you can, ...its been years since I opened one. You'll have to bend the metal tabs on the one end of the motor to open it up.

CAn you see anything when you look in the vents on the motor? I remember running an off-road truck w/ a brushed and getting a stick stuck in one of the vents. It was a tiny piece of bark actually and it jammed up my motor ...I was able to get it out w/ tweezers ...but took awhile as it was lodged in pretty good.