Replacing the carbon brushes on a Dyson vacuum cleaner motor is very cost effective so it’s usually worth trying before replacing the motor.
Checkout the video and procedure below to see how it is done.
Where to find the parts:
UK: Replacement Carbon Brushes and Springs
UK: Fully Assembled Brushes with Housing
UK: Full Replacement Motor
US: Replacement Carbon Brushes and Springs
Carbon brush replacement procedure
Remove the retaining screw from the brush housing

Remove carbon brush housing retaining screw
Pull out the brush housing from the motor body

Pull out the brush housing from the motor
Bend up the two tabs with a flat bladed screwdriver

Brush housing contact tabs

Lift the first tab with a screwdriver

Lift the second tab witha screwdriver
Lift up the contact over the tabs

Lift up the contact over the tabs
Cut the brush wire with wire cutters
Remove the brush wire and spring
Clean the area in preparation for soldering

Clean the contact for soldering
Tin with a hot soldering iron

Tin the carbon brush housing contact

Tin the brush housing contact
Tin the Carbon brush wire

Tin the carbon brush wire

Tin the carbon brush wire
Assemble the parts, not forgetting the spring

Insert brush wire through spring and into housing
Locate the wire through the hole

Insert the Dyson carbon brush into the housing
Solder the wire to the housing

Solder carbon brush wire to the contact
Push the housing back into position
Bend over the tabs with some thin nose pliers

Bend over the brush retaining tab
Keep your finger on the carbon brush while
you insert the brush housing into the motor body

Hold carbon brush spring in place

Insert carbon brush into the motor body
Secure the brush housing to the motor body with a screw

Replace the carbon brush retaining screw