Have the red Mcleod hydraulic clutch full set up. It shifts great 90% of the time but when driving sometimes, it'll switch and have engagement on the floor or no engagement and can't get out of gear. If I lightly tap the clutch pedal boom back to perfect. I look at the firewall adjuster push the main shaft in while screwing the nut out, it holds and drives great for a while, then boom goes out again. It's very intermittent. Is this air in the lines, or am I doing something wrong with the nut? Should the shaft going into the nut be loose or securely fit into the shaft?