The Direct Approach...
Martec folders have been around a long time, and they routinely refurb their older ones. Maybe a call (using that non-internet ancient thingy called a "telephone") to them might help...
They might have a deal on a used one or know of one or two for sale.
URL for purdy pictures and contact info is
http://www.martec-props.com/
Tell 'em I said hello. I have been using one of their Autostream feathering props for a decade and always chat with them for a minute visiting their booth at Strictly Sail in Oakland.
They can advise you on what details to look for in a used one, as well.
Cheers,
Loren in PDX