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I checked the alignment of the top bogies with my 4' level. There was about half an inch toe out in the middle. This couldn't be seen from the ground or inside the dome. I removed the fixing bolts and fitted another 12mm nut as a spacer only on the outer bolts. Once everything was tightened again the top bogies were now aligned.
I bent the stay rods at the top to better align the channel. The rods
were twisting the channel outwards. That helped too but there is still
some sticking. I fitted a second wedge under the channel to maintain uprightness.
The bottom bogies were out of alignment too. I re-drilled the shutter rib for one bracket and that solved the problem. The shutters now run much more smoothly but still stick occasionally at the top.
I must cure this infuriating problem before the dome is lifted into place. The observatory walls will add 1.5m or 5' to the height of the dome above the observatory floor. Making the top of the dome completely out of reach without a 4m+ ladder. I could fix pulleys to the zenith board to pull the shutters open and closed. I would prefer not to have to rely on such devices.
The friction is caused by the aluminium channels rubbing together. Or the skate wheels dragging on the channel. Usually as result of the bottom of the shutters being out of phase with the tops. This shortens the shutters and twists them diagonally.
I tried greasing the channel overlaps without obvious improvement. Perhaps plastic, file binder, slipped over the edges of one channel, would help? Plastic against aluminium can't be as bad as aluminium dragging against aluminium. I was still adjusting the lower bogies when it became too dark to continue. The sun never did show itself for long enough to make imaging worth the effort.
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