Power Drill emits a bright spark and stops. Can fix?
So.. I think i fixed it.. this video and others suggest that this might be carbon build up along the shaft of the motor causing the excessive sparking. Some places suggest taking a can of compressed air to the thing.. and I didnt have one so I used a homemade can of compressed air... my mouth.. seems to have worked. The sparks are now down to a minimal level which is apparently expected in a brushed motor, and the drill is able to run even at max speed which it wasnt earlier.

TLDR - Could be carbon build up along the shaft. If you cannot reach the shaft, clean with compressed air or blow hard with mouth.