FYI check the 7/8 master as there was a recall on them for this very issue. My 7/8" master is on the recall list but it's working. I'm planning to send it in shortly to get it replaced with the new valve design.
You can google Wilwood 7/8 Master recall and get the product numbers. Here's a link...
https://www.wilwood.com/Pdf/Recalls/RDCONL-17E030-0986.pdf
What is the Defect/Reason for this Recall?
Wilwood® believes the brake cylinder seal in the front circuit may become deformed, bypassing hydraulic fluid and resulting in loss of braking in front circuit. Unexpected loss of brake pressure and pedal feel in front brake circuit may increase the risk of a crash.
Riddler
