Hi. I bought a Makita cordless drill, model 8391D. Whilst drilling a pilot masonry hole it suddenly stopped. The battery had only just started to slow so I changed it anyway to a fully charged one and the drill was still dead? Someone has mentioned to change the brushes? Could this be the problem. The drill is only about ten months old. Any info appreciated.

It could be that the batteries died.

Hello Beverly, I would check for worn out brushes.

Look inside where the Battery terminals connect.
THey are flat metal springs inside the drills Battery hole.
Make sure the are not compressed down causing them not to touch the battery terminals of the battery.

ALso check the Brushes on the drills motor they may need replacing...

Selvol

You have to check the batteries with a new machine. If the new machine works ok then the rotor of the motor of the old machine is broken.

I think you will find that if you open the chuck fully you will see a cross head screw inside the chuck which you need to undo before removing the chuck. this secure the chuck from unscrewing while being used in reverse to undo screws. Once this screw is out a spanner is used at the base of the chuck to unscrew it from the shaft. this may need a short sharpe shock to get it to move.

Put the clutch on a high number, put the reverse on, hold the chuck tightly, lightly press the triger. If it does not come undone, make the clutch tighter (loer number).

If the battery was connected you probably shorted out the battery. Shake all water out of drill and let dry. get a battery that was not in water, try this. If still won't work you will have to bring to repair shop. If you try and take it apart it may be hard to put back together.

i would say its the switch!

but i would jump the motor directly to the battery bypassing the switch to be sure

try toolpartsdirect.com & go to makita & type in model #