After much Internet surfing and dealer inquiries in search of a Series 93 medium yellow filter for the lens I have purchased, I have determined that both b+w and Heliopan have discontinued this size filter and it appears that there is no longer any new stock available. I've checked with several used equipment dealers and came up empty there as well.
If anyone knows of any website that might deal with such an obscure item I would be most grateful.

I have a number of searches going on the big auction site but it may be some time before anything develops there
and since I need to locate one relatively quickly I am now trying to come up with other options. Unfortunately the kind of work I do precludes the use of gel filters as they are too fragile and I need to stick with a glass filter.

Going over the Schneider tech sheet on the lens it lists the screw in thread for accessories as 86x1mm. I assume that this thread would match the thread on an 86mm filter. This woud require removing the lens hood and filter holder ring and applying the filter directly over the front element. I'd like to find out if any one has done this and if it worked okay or if they had any problems with this set up.

If any one has any other ideas or found other solutions I'd be very happy to hear about them as we'll.
T hanks in advance
Hal