First of all adjust your tie rods to have the wheels straight ahead when the piston is about mid travel in the cylinder. The drag link is not forcing the valve actuator out of neutral. Remove that grease zerk in case the threaded end is too long and try your screwdriver pry again. Pry against the stud ball seat as shown and again on the other side.
If the actuator can only be pried in one steering direction, pin #23 in adjustment nut #24 may be broken and adrift obstructing the spool travel. Broken pin generally happens doing assembly so the question is has this cylinder functioned since the last time it was apart? Pic is a broken pin, small piece is the obstructer. Shank of a 1/8" drill bit makes a suitable pin.
If the actuator can be pried in both directions but the steering force does not change, spool bolt #22 may be broken.
Spool travel is very narrow, less than a 1/4" total so it doesn"t take much to cause problems. Misadjustment (#24), excessive wear, etc are also potentials, you just have to take it apart and check.
Last pic is a 310, your drag link will be different and some other minor changes but operationally the same.