NavList:

Eric, that picture definitely looks like the pellicle has degraded. They are very fragile things after all the years of storage. 

I have experimented with a few things to replace it. As Bill Morris suggests, I have the best results with plastic food wrap. I tried several brands - the high end stuff seemed to be better from an optical perspective. I stretch it in an embroidery loop. I used white glue on the recessed edges and set the pellicle frame on the plastic and put weight onto the back as it dries. 

Im not sure how to diagnose the index, however. Does the prism at the top of the periscope tube move at all?

Note that there is an optical path that allows the Nav to see the bearing ring that is at the bottom of the mount - did you put "Diffuser in" on the diffuser to obscure this view?  it points straight up and may be overwhelming your view thru the periscope  You might just cover that port with some masking tape instead.  

Also make sure that the shade carousel is not jammed - if stuck on one of the darker filters you may not see anything at all.

I hope this helps  

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