So I just installed a new slave and master cylinder in my 2006 WRX Limited and spent weeks trying to bleed it with no progress when I noticed it seemed to be leaking from the round plug looking thing on the bottom of the master cylinder. I took it in to a Subaru dealership and they told me it must be defective so I exchanged it for a new one and it does the same. I started thinking it might be the line connecting to it and what I'm seeing is just the fluid running down from there but I tightened it as much as possibly and it still leaks. Should I try replacing the whole line?


Follow up, what is the function of that plug looking piece?