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What to do if you believe that there is a backlash in the gearbox
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First if you think that there is a worm gear mesh issue, you are probably wrong. If you think there is backlash, it is
almost certainly from a different source, so look elsewhere first.
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Check the mesh of the spur gear reduction set. With your thumb and forefinger gently attempt to move the
middle spur gear back and forth. There should be a slight amount of movement so that the gears do not bind
up; however, it should be slight. If there seems to be too much looseness, contact Astro-Physics for further
help.
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Check to be sure that the two shoulder bolts that secure the spur gears are snug. Important: the bolts should
be snug...Do Not Overtighten, as they can break or damage the gears.
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Check that the entire motor/gearbox is securely fastened to the axis housing. There should be a very small
amount of front-to-back rocking that is possible due to the spring loading mechanism, but there should be no
discernible side-to-side movement. If you feel side-to-side play, contact Astro-Physics
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IMPORTANT! Do the following with the mount powered ON. It should be UNPARKED and tracking should be
STOPPED. There are two or three small screws securing the worm spur gear to the worm. A screw may be obscured
by the top gear. For that reason the mount is powered on so that you can rotate the gear using the direction buttons at
12X or 64X. If you would attempt to turn the R.A. gears by hand, you would lose your PE correction; therefore use the
direction buttons.
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Check that the worm’s spur gear is securely attached to the worm shaft. The 2 screws must be tight. (Be
careful, however! They are small screws, not automotive lug nuts!)
Worm Spur
Gear Screws (2)
Worm Spur
Gear Screws (3)