Doug,
To do it properly (IMHO), the air scoop (on which the nozzle is fitted) will have to come off. Close the cold air vent. Remove two screws (one each end) on the outside of the scoop near windshield.
Also remove chrome grill on scoop - 3 or 4 screws seen with hood open.
Now, look into the gap under the scoop. Should see 4 or 5 more screws. Loosen each a few turns - no need to completely remove.
Now lift scoop off.
Remove elbow joint/water pipe from nozzle.
Slide off spring clip holding nozzle.
Fit in reverse order of removal
naj
65 230SL
68 280SL