PUT IT BACK TOGETHER

1 Fit armature to end plate

If you can, carefully pin back the brushes by their braided wires. Insert the commutator with its oil slinger and any shims. Alternatively, wriggle it in while pushing the brushes back manually.

2 Refit casing

Refit the casing, aligning the marks you made on dismantling. Keep your thumb on the end of the spindle or the magnets will pull it up, snatching the commutator back out of the carbon brushes.

3 Align bushes

Fit the screws loosely. Connect the motor to a 12V supply. Tap it very gently with a heavy hammer. Tighten the screws a little, tap, tighten and repeat until it runs at full speed and the screws are tight.