[. . . ] Do not operate charger if it has received a sharp blow, been dropped, or otherwise damaged in any way; take it to a qualified serviceman. Do not disassemble charger or battery cartridge; take it to a qualified serviceman when service or repair is required. To reduce risk of electric shock, unplug charger from outlet before attempting any maintenance or cleaning. The battery charger is not intended for use by young children or infirm persons without supervision. [. . . ] Sound of cooling air comes out during cooling, which means no trouble on the charger. ­ Trouble on cooling fan ­ Incomplete cool down of battery, such as, being clogged with dust The battery can be charged in spite of the yellow warning light. Check the sound of cooling fan, vent on the charger and battery, which can be sometime clogged with dust. The cooling system is in order although no sound of cooling fan comes out, if the yellow warning light will not flash. The products should be sent to repair or maintenance, if the yellow warning light will frequently flash. Conditioning charge can extend the life of battery by automatically searching the optimum charging condition for the batteries in every situation. The battery employed in the following conditions repeatedly, will be worn out shortly, and yellow warning light may flash. Recharge under broken cooling system The charging time of such battery is longer than usual. If you leave the battery cartridge in the charger to prevent spontaneous discharging after full charge, the charger will switch into its ``trickle charge (maintenance charge)'' mode and keep the battery cartridge fresh and fully charged. Always stop tool operation and charge the battery cartridge when you notice less tool power. Let a hot battery cartridge cool down by inserting it into the charger. Charge the Nickel Metal Hydride battery cartridge when you do not use it for more than six months. Never use it for other purposes or for other manufacturer's batteries. When you charge a new battery cartridge or a battery cartridge which has not been used for a long period of time, it may not accept a full charge. You can recharge the battery cartridge fully after discharging it completely and recharging a couple of times. If you charge a battery cartridge from a just-operated tool or battery cartridge which has been left in a location exposed to direct sunlight for a long time, the charging light may flash in red color. charging will begin after the battery cartridge is cooled by the cooling fan installed in the charger. 70°C, two charging lights may flash in red color, and when approx. If the charging light flashes alternately in green and red color, charging is not possible. The terminals on the charger or battery cartridge are clogged with dust or the battery cartridge is worn out or damaged. Any of the following conditions indicates damage to the charger and/or battery cartridge. 1) The charging light does not flash (green) when the battery charger is plugged into a power source. [. . . ] Be sure that the speed change lever is set to the correct position before operation. cAUTION: · Always set the speed change lever fully to the correct position. If you operate the tool with the speed change lever positioned half-way between the ``A'' side (2) and ``B'' side (1), the tool may be damaged. CAUTION: Always be sure that the tool is switched off and the battery cartridge is removed before carrying out any work on the tool. [. . . ]