Introduction
Use this guide to service the piston in a Makita Jack Hammer HM1203C 2010.
Wherever there’s grease, make sure to clean it off and replace it with new grease. The recommended grease is Makita 181490-7.
Tools
Parts
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Pull the handle assembly away from the hammer, but do not completely remove it yet. It's still connected to the hammer by a power cable.
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Use a pair of snap ring pliers to expand the snap ring on the front of the hammer.
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Remove the snap ring.
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Compress the spring and hold it down while you pull the two retainers out of their slots and remove them.
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Use a pair of snap ring pliers to expand the snap ring securing the bolt holder.
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Remove the snap ring.
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Grasp the bolt holder, rubber ring 24, and the two metal sleeves below it, and lift it off of the cylinder.
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Use an angled pick to lift the O-ring 35.5 out of its groove on the bolt holder.
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Remove the O-ring 35.5.
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Use a long punch, long flathead screwdriver, or a thin, long bar to push the bolt out of the bolt holder.
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Remove the bolt.
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Use a pick to pry the striker O-ring 31.5 out of its groove on the striker.
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Remove the striker O-ring 31.5.
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Slide the fix guides and the rubber plate out of their slots on the housing and remove them.
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Rotate the crank shaft and the connecting rod so that the rod is vertical and the end is at the very bottom of the housing.
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Use an arbor press and a custom punch to carefully press the crank shaft, bearing, and gear assembly out of the housing.
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If you don't have access to a press or custom tool, use a punch and a hammer to tap the crank shaft until the whole crank shaft, bearing, and gear assembly starts to slide out.
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Use a pick to pry the piston O-ring 31.5 out of its groove in the piston.
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Remove the piston O-ring 31.5.
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To reassemble your device, follow these instructions in reverse order.