kilix

Nick, your list of Orion's doubles was extremely enjoyable to follow, so I will follow this one too, looking forward to clear skies (hopefully I will live that long :-) )!

7 hours ago, happy-kat said:

Is the commulator the black centre bit please?

yes. The cylinder structure out of which the axis protrudes. If it were not covered with dirty grease in this photo, you could've seen copper commutator bars.

When you disassemble the motor, you can gently pull out the white plastic brushholders and then you can also pull out the entire rotor+commutator assembly. Makes cleaning easier.
Again, there are tiny tiny washers on the axis, so be careful.
Just be gentle when pulling the axis out of the bronze bushing, pull only along the rotation axis, do not wibble-wobble the axis, or you will bend it.

1 hour ago, happy-kat said:

Good read. You've probably got a spare motor now have you cleaned your original as well?

nope, I was on a verge of buying a new motor, but then I thought "it's already screwed up, no further harm will be done, when I look inside" and I did that. What encouraged me the most is the fact, that there is no decent SkyWatcher parts supplier in our country, so buying a new motor from UK and paying for postage would be like 50-60€. The only other option was to buy the entire tripod+head for 90€, which I can buy in Slovakia.

I will probably do this procedure to AZ motor too, as a precaution. AZ motor works well now, but I suspect, that it will be filled with that lard-grade schmoo too and it's only a matter of time before it starts failing.

Hey guys,

Sorry for necroing this old thread, but I figured, that it may become useful for someone like me, who faces the same problems with quirky movement of alt motor of a SkyWatcher AZ GoTo mount. So, I've read pretty much everything on the internet regarding this issue, nothing helped, what I did is this:
Disassembled everything, took out the motor+gearbox assembly. Tried to run it, motor running slowly still. So, next logical step is to remove the gearbox and search for culprit there. I did that, you don't need to worry about not being able to assemble the gearbox again. It contains about 6 gears, there is literally no possibility to assemble it wrong, those gears wont fit any other way. They will only fit the way they are supposed to be. Be careful though, there is one infinitesmall washer on the last bronze gear, don't lose it like I did and then I searched for it for 2 hours.
So with the gearbox out of the way, only the motor + pinion remained. Tried to run it, still no improvement.
Last thing to try is to disassemble the motor.
Careful here, it's almost like clockwork. Brush holders are thin like matches, carbon brushes are about 1x1x3mm big, which is not big at all. The retaining springs are made of some nice material, looks like gold coated maybe, but they are really small and can jump out during disassembly.
Here is the the motor, you can see the really tiny brushes in right-center:

and as you can see on this photo:

the commutator is covered with schmoo. So I cleaned the commutator, brush holders and brushes with tetrachloroethylene, then I applied contact spray. The commutator+brushes are shiny like new. Assembled the motor, BAM, it runs crazy fast and steady.

Apparently, the grease from gearbox entered the motor and fouled the commutator+brushes. So, next logical step is to remove all the grease from the gearbox, replace it with sane amount of nice vaseline and assemble everything back together. I also recommend removing the cheap grease from the huge aluminium gear and teflon pads and replacing it with some more useful lubricant.