"For break in, Ill start by saying everyone hass their own tricks and theirs is the only one thats right". quote from burnineyes. He is correct. ask 10 people and get 11 answers. This thread is about a slash 12t motor so I will assume that that is the motor you are asking about. this method will work with any closed end bell motor( slash, blitz, sc10, strike).
A: the first thing you will want to do is try and bend the brush holder in a small arch to put more pressure on the brush. it will look something like this. ( O) ). the circle would be the comm. and the line would be the brush holder/spring. this will put more pressure on the comm. and help hold the brush in place.
B: using brasso or any kind of brass polish, put 5 drops on both ends of the motor on the bushings. use a 4 cell pack to spin the motor. this will polish the bushings and shaft on the motor so that it will spin freely with very little friction. DO NOT USE ANY TYPE OF OIL. the oil will adhere to the bushing first and will not allow the polish to do its job. this will only work with a motor that has not been ran because of the design of the oillight bushings. run the motor until the polish is dark black. Repeat 3 times. then put oil on the bushings.
C: using water, sub-merge the motor in water and run with a 4-cell pack. this will break in the brushes and keep the motor cool. the water will also put a small load on the motor to aid in break-in. I do this for about 30 min. I will also change the water every 5-10 min. doing this will help flush the motor out.
D: flood the motor with motor spray to get all of the water out of the motor. oil the bushing when the motor is dry. Mount the motor in the truck and drive for one pack on the road or parking lot. do not drive in grass just yet. you want to finish seating the brushes without a lot of load. the grass will create to much drag and heat up the motor.
When finished, you can run your truck silly. just keep an eye on the motor temp. Heat is the worse enemy of the magnets.
REMEMBER: these motors run best just before they blow up.
I hope this helps and remember, 10 people 11 answers!!!!!!!!!!