@DavidB1126 gave some good advice there.
Brushless is always the better choice. But you have to invest in a LiPo charger if you don't already have one. And you need to know how to store and care for LiPo batteries. This is extremely important.
How old are you? I'm only asking because we get...
Have you removed the motor to see if it will spin? Bearings could have rusted and seized. Traxxas motors are not known for their reliability.
As for the slipper, post a pic. You can attach pics with a button below the reply window where you type.
And welcome to RCT.