How to properly adjust Eaton clutch with hydraulic linkage

Hello everyone,

I have an eaton advantage easy pedal clutch on an RTLO18918B transmission. Bought the truck a year ago with a stiff clutch pedal and can't fix it yet. Changed the master and the slave cylinder already. Grease the bell house grease fitting. The free play looks okay and the 1/2" measurement looks also okay. But the clutch pedal is still very stiff and hard to depress. Haven't pull a load since then. I drove the truck for a few miles and shifting between the gears wasn't so smooth on all the gears. What could be the problem? Hope you could help me out.