My 240z has hard brake lines connected to the stock brake proportioning valve below the master cylinder. There is fluid seeping from around these hard lines even though the nuts on the proportioning valve are cranked down tight. I'm going to be upgrading my master cylinder to install 4 piston calipers which I've had on hand for a while and can not seem to find somewhere to purchase a new proportioning valve (which I believe is the issue). Thank you for your help and any comments or thoughts would be greatly appreciated!