This question mention that it is common to see sparks inside a drilling machine.
It is not uncommon to see sparks at the interface point between the carbon brush and the commutator as the motor operates.
So, is there a particular kind of spark inside the drilling machine that is dangerous and requires stopping work immediately and getting it fix? and also, do old drilling machine have fewer sparks than new drilling machines (the question mentions that old drilling machines produce more sparks, while the answer mentions that new drilling machines produce more sparks, both statement are contradictory to each other)?
I went through a few forum threads where people said sparks inside brushed drill machines are common, but all of them mentioned old drill machines
The amount of sparking will often reduce as the brushes wear in during use of the tool.