Water will f**k it up after a couple of weeks. Depends how often you ride
Bleed it from the salves up take the levers off and hold it so the hole is vertical and at the top
Don't worry about 3 threads just undo it until you can push fluid out. Keep pushing until no air, do it back up, tap the hose and slaves while keeping the lever up, then bleed a bit more fluid out that should get the last bit of air out