[Eljaro]

I drove the car again after tightening the six 5/16 bolts of the pressure plate.
I checked them again yesterday after a ride. They were not as TIGHT as they should be. So there is some movement there which looses them up.
So I bought six socket head screws in DIN 12.9 strength (which is higher than grade 8) with shoulder. The 30mm long screws did not have shoulder, so I had to buy the 40mm long ones and cut them to size. I used hardened steel washers since the head of these screws are very small and tend to sink into the pressure plate metal.
I also used blue locktite and tightened to 28 lb/ft.
I will have regular checks on these screws, easy to do through the fork hole.

This is one disadvantage of aluminum flywheels I was not told about.

Regarding twobjshelbys problem, it is either the master or slave cylinder.
If by pumping the pedal the line purges itself empty it is probably the master cylinder. It happened to me once when I wrongly used DOT 5 brake fluid. The inside of the cylinder got corroded and leaked past the piston.
Disassemble the master cylinder ( depending on your setup you can do that without removing it from the car) and check visually.