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Makita Hammer Drill Repair – Replacing the Gear Assembly (Makita Part # 126353-0)

"The gear assembly is a major component of
your cordless drill. The transmission has a series of gears that
increase the amount of torque the drill produces. The transmission has two torque settings and
a selector to change between them. The clutch is adjustable and allows you to
set it to cut out at a specific torque. This is helpful in driving screws to a specific
depth. Over time, the transmission will wear and
eventually fail. Often, failed transmission won't drive it
all at one torque setting, but will still work on the other. A failed clutch might not slip at all, slip
constantly, or slip at a lower amount of torque than it should. Replacing the gear assembly is a repair that
you can do yourself and I'm going to show you how. Hi, I'm Mark Sodja. Do-it-yourself' repairs like these are easier
than you might think. From lawn machines to cordless drills, kitchen
mixers, outdoor grills. Our how-to videos walk you through each repair
from start to finish.

Doing it yourself means never having to do
it alone. Let's get started. I'll begin by removing the chuck from the
drill. First, I'll remove the chuck screw. It's, reverse-thread. With the retaining screw removed, now I can
remove the chuck. First, I'll set the transmission to the low
setting. Then, I'll take large Allen wrench and chuck
it into the Chuck. Now, I'm going to quickly strike the Allen
wrench with a mallet. The sudden force will break the chuck free. Now, I'll remove half of the housing.

Now, I have access to the gear case and motor
assembly. Next, I'll lift this assembly away from the
housing just enough so I can separate the gear case from the motor. As I do this, I want to be careful that I
don't lose the two springs on the backside of the selector. Now, I can begin installing the new gearbox. There's a small pin that fits onto the spring
on the selector tab.

Allen

That pin needs to fit over one of the two
springs on the selector. To do this, I'll place the pin inside the
spring, then compress the spring with the tab as I slide it back into the selector. Now, this is ready to go into the housing. Now, I'll reinstall the gearbox onto the motor. I align the gears and slide the two together. I'll line the gearbox with the housing and
snap it into place. Now, I'll reinstall the housing, and secure
it with the screws. I'll finish up by reinstalling the chuck. I'll use the Allen wrench to hand tighten
the chuck and I'll secure the chuck with the retaining screw. I'll place it inside the chuck and thread
it into place. Again, remember that it is a reverse thread. That's how you can replace the gear assembly
in your drill. Be sure to check back often for new videos
and expert advice.

If you found this video helpful, give us a
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As found on YouTube

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