The longs are what hold the cell down. The shorts are the ones that establish the spacing at three points to change the plane of the cell with respect to the optical axis. A missing long screw is harder to deal with than a missing short, because changing the spacing of the other two points can lift the short screw away from the underlying ring. With missing short screw, you can put a thin spacer under the long one and tighten it down, then use the other two for collimation.
Great info! I've not done any research on them, and the original manual just talks about the "squaring on" and if incorrect to "adjust the screws," but no details. I've not yet gotten to look for Airy disk patterns, so I'm trying to touch as little as possible.
(and, IIRC, these screws are some Japanese special thread that hasn't been machined in 50 years or something. ?)
Thanks, Chip! Much appreciated