The fork will appear to be slightly loose when you slide it over the throwout bearing of the ZF clutch pressure plate. When you install the bell housing, it will still appear to be slightly loose. One thing to note is that the pivot ball for the clutch fork should be securely tightened against the bell housing. Not that tightening the pivot will make any difference, just thought I'd mention it because that's the way it should be installed (fully seated). Once the slave cylinder is installed, the hydraulic piston will take up a slight amount of the play in the assembly. Part of the reason that the fork is slightly loose is that this minimizes the friction of the fork against the throwout bearing. It more or less just "rides" the throwout bearing assembly.
