Starman, The azimuth movment in mine was almost binding until some type of plastic ring fell out from somewhere. This was not the plastic washer, but a knurled ring about 50mm in diameter, 5mm thick, with the cutout area of the ring 40mm in diameter. See if you can locate this ring and remove it; it might help with the movement. My refractor weighs 10 lbs. and the azimuth seems pretty smooth.
Oddly, my accessory tray only has holes for (3)1.25" oculars. The Twilight II only seems to weigh 23 lbs according to my scales.
I agree about the instructions.
Otherwise, I think I'll be very pleased with this mount.
Photo of the plastic ring:DSCF0462.jpg
Rachal posted a picture of a “mystery” part that fell out of his Twilight II mount head.
Without this part, his mount seemed to function much better.
This caused me to examine my new Twilight II mount.
The use of a strong flashlight revealed a gap between the mount head and the plastic washer.
The gap was probably no more than a few thousands of an inch.
I removed the mount head from the azimuth shaft.
I had previously greased the plastic washer that acts as a bearing plate for the head to rotate upon.
The head was making contact only on the inner portion of the plastic washer.
An inner ring, about a quarter of an inch wide, was missing grease.
The outer portion of the washer still had grease on it, apparently undisturbed.
I examined the bottom of the mount head and found the “mystery” part at the shaft entrance.
It is a plastic bushing, press fitted into a machined holding cup.
I could feel that the bushing was not quite fully seated. It wasn’t quite flush with the head’s base.
Maybe it was jutting out a few thousands of an inch. Bingo!
With quite a bit of force, I used my fingers to extract the bushing.
I had to go around the perimeter and slowly nudge it out. It took a while but it came out intact.
The holding cup, drilled into the mount base, was beautifully machined.
The plastic bushing had ridges on its exterior, similar to the milling ridges on a coin.
These allow the bushing to fit tightly while still being flexible enough to allow insertion.
Apparently the bushing was not quite “square” when it was pressed in.
Some of the milling was shaved off and protruded slightly above the top surface of the bushing.
I got some 3M 400 sandpaper, put it on a flat table, and proceeded to slide the bushing on it.
All of the little protruding spikes were eliminated and the bushing top was nice and flat.
I placed the mount head back on the tripod, minus the bushing.
The mount made full contact with the flat washer, no gaps visible using a flash light.
This proved that the machined bushing in the top of the mount was deep enough.
I removed the mount head, inserted the plastic bushing and reinstalled the mount head.
Everything worked fine and there were no gaps visible using the flashlight.
These damaged “milling” ridges could explain the varying reports about “break in time”.
Given enough time, these little protuberances could dig their way into the plastic washer, allowing the mount head to fully seat.
It seems a simple redesign (beveling the bottom edge of the plastic bushing) could fix this.
The top edge is already rounded, allowing for easy insertion into the holding cup.
In summary, the “mystery” piece is a plastic bushing for the bottom part of the azimuth shaft.
It is NOT a bearing plate and should not be functioning as such (as it was in my mount).
This plastic bushing is essential and should not be left off.
It provides stability for the mount head, especially if used for a single telescope with no counterweight.
If used this way, over time the topmost bearing will become hourglass shaped instead of cylindrical.
I had quite a time of it removing my bushing.
Rachal’s bushing must have been much looser.
If it was protruding out far enough, then that is why the mount head would not seat properly.
I want to thank Rachal for posting that picture.
Without it I would never have known to look.
I suspect Rachal’s plastic bushing might have been damaged during assembly at the factory.
I would recommend contacting ES regarding a replacement plastic bushing.
It’s very easy to replace. Just be careful to put it in straight and not damage that milling.
CN to the rescue again!! Thanks very much for this information "Uplateagain"! Please use paragraphs next time though
My Twilight II just started getting progressively worse stiffness in the Azimuth until completely binding. This thread really helped tremendously. I disassembled the head and found the bushing, removed it, felt around for any burs, didn't find any, then sprayed silicon lubricant inside of the head, and bushing housing and onto the bottom / top of the plastic washer. Carefully reassembled everything, and while its not smooth as butter, (never was) it is back to original condition which is smooth enough and no real effort needed.
I think the cause of this binding is the process of lifting the mount while putting any amount of upward pressure against that axis (which is necessary when one side is heavier than the other) thereby skewing the bushing. But that's just a guess. I think I'll move the mount without any heavy scopes attached in the future so no upward pressure is applied to that axis in support of the heavier side from tipping. Thanks again for sharing this!