my motor is acting wierd

[Notochord]

so whenever i go out to drive my car. it starts to drive all normal, but after a minutte it just stops. so today i took it in and i was trying to figure out the problem. my motor wires arent messed up there getting a good connection. so then i looked at the motor. when ever i push on the endbell of my motor it works but if i let go then it doesnt work. theres a hole in the motor so when i looked in and pushed the motor it was sparking a lot so i thought that the brushes are worn out. because its getting a bad connection. do you think it is the motor and how do i take out the brushes sorry for all these stupid questions but it helps thanks.