As far as the lift cyl- if it's a 2 stage upright then the hoist cyl will be a simple, 1 ram inside a shell ordeal- very easy to re-pack. If the upright is a 3 stage- the hoist cyl will be a telescoping quadruple step up which is best left to a hydraulic shop for repair.

As far as the inching spool- there is an adjustment built in to the actuator rod for the master cyl's- there are 2 master cyl's- 1 on the right (as seated on the machine) which activates the brakes only, and 1 on the left which activates the inching spool & brakes at the same time. Adjust these actuators so there is about 1/2" play in the brake pedal (measured at the pedal itself) before the piston in the master cyl begins to move. If this play is already present & the inching mechanism isn't working correctly further diagnostic work will be needed.

As swoop said- there's no adjustment for the spool of the hyd. control valve. If the tilts are drifting then it's either packing in tilt cyl's that's failing or a worn hyd control valve. As stated- hydraulically lock off 1 cyl at a time & see if drift continues.