8 Care and maintenance
CAUTION
Disconnect the supply cord plug from the power out-
let.
en
8.1 Care of cutting tools and metal parts
Remove any dirt adhering to the surface of cutting tools,
the chuck and drive spindle and protect their surfaces
from corrosion by rubbing them with an oily cloth from
time to time.
Always keep the connection end clean and lightly
greased.
8.2 Care of the machine
CAUTION
Keep the machine, especially its grip surfaces, clean
and free from oil and grease. Do not use cleaning
agents which contain silicone.
Never operate the machine when the ventilation slots are
blocked. Clean the ventilation slots carefully using a dry
brush. Do not permit foreign objects to enter the interior of
the machine. Clean the outside of the machine at regular
intervals with a slightly damp cloth. Do not use a spray,
steam pressure cleaning equipment or running water for
cleaning. This may negatively affect the electrical safety
of the machine.
8.3 Maintenance
WARNING
Repairs to the electrical section of the machine may
be carried out only by trained electrical specialists.
Check all external parts of the power tool for damage
at regular intervals and check that all controls operate
faultlessly. Do not operate the power tool if parts are
damaged or when the controls do not function faultlessly.
9 Troubleshooting
Fault
The machine doesn't start.
12
If necessary, the power tool should be repaired by Hilti
Service.
8.4 Replacing the carbon brushes 7
NOTE
The indicator lamp with wrench symbol lights up when
the carbon brushes need to be replaced.
DANGER
The machine may be operated, serviced and repaired
only by trained, authorized personnel. This personnel
must be specially informed of any possible hazards.
Failure to observe the following instructions may result in
contact with dangerous electric voltage.
1.
2.
3.
4.
5.
8.5 Checking the power tool after care and
After carrying out care and maintenance, check that all
protective and safety devices are fitted and that they
function faultlessly.
Possible cause
Interruption in the electric supply.
Carbon brush automatic cut-out ac-
tivated.
On/off switch defective.
Disconnect the machine from the electric supply.
Open the carbon brush covers on the left-hand and
right-hand side of the motor.
Take note of how the carbon brushes are fitted and
how the conductors are positioned. Remove the
worn carbon brushes from the machine.
Fit the new carbon brushes just as the old ones
were fitted (spare part numbers: carbon brushes
AO ML 100‑127 V: 39577; carbon brushes AO ML
220‑240 V: 39576).
NOTE Take care to avoid damaging the insulation
on the indicator lead as you insert the brushes.
Close the carbon brush covers on the left-hand and
right-hand side of the motor and tighten the retaining
screws.
NOTE Once the carbon brushes have been re-
placed, the indicator lamp no longer lights when
the machine is reconnected to the electric supply.
maintenance
Remedy
Plug in another electric appliance and
check whether it works. Check the
plug connections, supply cords and
extension cords, PRCD and electric
supply.
Replace the carbon brushes.
See section: 8.4 Replacing the carbon
brushes 7
The machine should be repaired by
Hilti Service.