To replace the W/S switch, you must remove the instrument cluster (a PITA).
1.) Remove the steering wheel, and place a towel over the steering column.
2.) Remove the ash tray & receptacle.
3.) Remove the Heater/Temp Control panel.
4.) Reaching inside & behind the Instrument Cluster on the left side;
(a) Disconnect the 2 connectors for the Cluster (access thru the Heater Control Panel opening).
(b) Disconnect the speedometer cable behind the speedometer.
(c) Remove the 5 Cluster fasteners (screws above & below the Cluster, AND the nut behind the right side of the Cluster, accessed thru the removed ashtray hole).
5.) The Cluster should now be free enough to pull the Cluster far enough out to disconnect the W/S wiper connector on the back of the Switch.
6.) With the Cluster removed you can now remove the square knob on the Switch lever, and replace the Switch.
This is also a good time to 'sanitize' the appearance of the instruments, lenses, and replace all the bulbs. (I recommend LED's.)
Keep Band-Aids handy for the cuts you'll receive.
Neil