96 Golf PS leak

96 Golf has lost most of the PS fluid. Leak is easily tracable to a metal angled hose coupling. On one side a hose is clamped to this coupling but on the other side the coupling has a groove for an O-Ring and the coupling simply pressure fits into a cavity in the PS pump body. The O-Ring provides both the fluid seal and the mechanical connection.

I repaired this 6 months ago but I used a hardware store O-Ring which the Pentosin CHF 11S fluid has digested and I have the leak again. I need to find a ring that is resistant to the fluid. VW dealer does not sell the ring but is eager to sell me a new PS pump. If I can get the right ring this should be a 15 minute, 59 cent repair. Has anyone solved this one before?

WP