I've tried to find anybody who will open the pressure chamber and put in a new diaphragm but so far to no avail. So I bought one of Brian Holms ($140US) and all is right with the world. EXCEPT, I believe there are more than 4 505 Turbos driving around and we all are going to need one eventually. I have some spares but one is failed and two are old (I'd hate to put an old one in just to have it fail quickly).
The link here is for the "universal" but the pressure canister is shorter and one would have to cut off the original bracker and bolt that on to the "universal".
http://www.amazon.com/gp/product/B00BD9BWEK/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1
Where do we go from here (or have you already run down this road?)