Clutch Master Cylinder Leak

[CYYJ]

When you found the protector, Honda part number 45512-MA6-006, missing, or dislodged, did you replace it back into position correctly? It can be inserted into the housing both correctly, and incorrectly.
You want it inserted so that the shoehorn looking part is in the upward position, and there is a gap between it and the floor of the housing. This is very important. If it is inserted backwards, the corrector will be flush with the floor of the housing and BLOCK the return flow of the brake fluid and lock things up!

There is a picture of the part that Larry (@Igofar ) is referring to at this post: Brakes - Operation of the Master Cylinder. The part is the same in both the brake & clutch master cylinders, and I believe that the design of the ST 1100 and ST 1300 master cylinders is similar if not identical.

Michael