There's no adjustment on the hydraulic clutch with internal slave/throw out bearing, and I think they come as a sealed set with the master, hose and slave as a unit. With the tranny in neutral try pumping the clutch pedal five or six times, ending with it fully down and then quickly see if it goes into gear smoothly. It sounds like you've got a clutch R&R in your future. Since you have to drop the tranny to change out the slave, I'd be ready to invest in a new pressure plate and disc, and maybe having the flywheel cleaned up with a milling machine cut depending on how it looks. It doesn't pay to scrimp with this type of internal slave.