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I've got a couple different Plath sextants whose index shades, through heavy use over extended periods,  have gotten loose to the point they now have a tendency to  not stay out of view -- flopping back down when the sextant is being used.

Tensioning the shades, or removing and replacing them, seems to require a propriety pin wrench that I can't find anywhere. Anybody have any alternative methods and tools? Or is there some other obvious solution that I'm overlooking?

This has been an ongoing problem, and a few years ago, I found a hobbyist who had manufactured his own solution. When I inquired, he kindly made another and sent it to me. Unfortunately the pins didn't last long. They sheared off negotiating a particularly tough one. 

Carl