Scope mount has some slack in vertical motion

Hi, I’ve noticed recently that my Celestron NextStar 8SE alt-azth mount has some slack (or slop) in the gears only in the vertical direction. Wonder how I can remedy that situation? Do I need to bring it to Astronomics for a work-over or is there something else I can do? Any advice appreciable - thanks.

Here are a few resources to check if you want to try yourself:

Thank you so much Tom. These will likely help a lot.

So my continuing saga on my altitude movement in my mount; I seem to have the clutch adjustment okay according to the videos
I watched, however, now when in aligning the slew in fast speed appears fine but when centering in the eyepiece and changing direction again in altitude the scope doesn’t move but i hear the motor going. Not sure what would cause this or how to fix it. Any suggestions welcome.

Not to sound rude, but this mount will never be slop or backlash-free. They were not intended to be. They were designed and priced to be simple grab-and-go mounts for entry-level visual observing. The housing and tripod are all plastic and lightweight materials.

Some slipping is also normal in the alt and az drives, that way if it’s overloaded or crashes into something, it slips.

Don’t get me wrong, it’s all good and fun to try and perfect entry-level equipment ( I love the challenge and do it all the time), but if you want a sturdy, slop, and backlash-free mount, an upgrade is in your future. Don’t forget, out at CRO we have a second pier/mount in the roll-off room. It’s a CGEM II EQ MOUNT, it’s rock solid and you are welcome to use it anytime.

Hi Andy, thanks for the info. I do realize that it won’t be free of slop or backlash, however, it isn’t working like it used to. It always worked fine in alignment mode and now when changing vertical direction it doesn’t move and that isn’t normal at all.

Can I ask a few questions?
Did you buy it new?
How long have you had it?
Have you double-checked the power supply by using a deep cycle battery and 13.8 volts?

All astronomy go-to mounts act crazy and do not slew right if they have voltage dips and or amp spikes. Maybe it’s trying to draw too many amps and the power supply isn’t keeping up. This is something very critical to all mounts. Voltage has to be at 13.8 and amps be in the 5-10 range. For example, I run my mounts off a 100ah Lithium power supply with voltage regulators to put out exactly 13.8 volts.

If it’s not a mechanical issue with the mount slewing, I would check the voltage/amps to rule it out.

Certainly - i did buy it new (was a gift) and it is 2 yrs old. Ive heard that the Nexstar mounts typically last a long time. I use an external battery and it was charged almost full.


Have you checked the exact voltage? Do you have a multimeter? You should have a multimeter measuring the voltage when the mount tries to slew and see if there is a voltage drop or anything. Just because the external battery was “almost full” doesn’t tell you the exact voltage. If the voltage dips down into the 11’s or low 12’s, mounts can quit slewing.

I do have a volt/amp meter, however, the current battery has been in use for the same time as my telescope and never had any issues except when the battery needed charging and it wouldn’t even allow me to turn on the mount - and that was pretty obvious. It slews on the fast speed okay but on the slow speed for the fine adjustment for eyepiece centering it stops after switching from up to down or visa-versa. Never saw that issue before. I can try the ac/dc plug and plug the mount directly into a wall outlet and see if it still does the same behavior.

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