Hi,
I've got the same on the rear of mine. There should be 12 clicks of adjustment, each click roughly 1/2 to 3/4 of a turn.
Most drivers prefer the Spax about 2 - 4 clicks away from minimum, mine are on setting 2 as I like my fillings to stay in my teeth. With your screwdriver, unwind the adjusters fully anticlockwise, you should feel when they come to the end of the adjustment. Then wind gently clockwise and you should feel it click into each setting.
I went up to 6 once and felt every ripple on the road. Probably great for a track day but not our pot holed roads.
Cheers,
Adam
TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, Single Pipe Exh, 3.08 Rear, 200lb Spax & Solid Bushes, Anti- Dive, Granada Vented Discs & Calipers, Braided Hoses, Green Stuff, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 5 Spokes and Cruise Lights. No Door Stickers. Mine since July 1986, V8 from 1991