When I bought my 1984 Eagle, one of the broken bits was the wiper function: Only one of the switch positions worked (high), and the wiper movement was actually very slow, sometimes stopping entirely. The 'intermittent' position did not work either.
After reading up on the subject of replacement switches here in the forums (turns out there is a 1980's Ford truck switch that is ALMOST a replacement, but it doesn't hook up the 'squirt' function), I decided to remove and repair my switch, rather than replace it. I'm writing this up in case it can help anyone else with the same ambition. I apologize for the lack of pictures, but other posts here in the forum have some good pictures of the switch itself...
1) Removing the switch:
I followed the advice of some other posters and got to it by removing the 'Select Drive' panel and reaching through the hole. Although I have big fat weight-lifter fingers, I was able to get 3 fingers on the back of the switch. My problem was the slotted retainer nut that holds the shaft in the recessed hole in the dashboard. Because this is about 1.5 inches deep in the 'well', I was unable to get enough torque with my tiny screwdriver to spin the nut loose. I couldn't use the side of the hole as a fulcrum to get better leverage, because my dashboard is brittle as heck, and I was determined not to break off another chunk of it.
The breakthrough was when I discovered that I could get my 3 fingers on the back of the switch and turn it about 10 degrees (you can't turn it more than that because the hole in the dash is keyed to fit the shape of the shaft). I found that, while I couldn't spin the slotted nut with my screwdriver, I COULD lock it in place while I turned the back of the switch a tiny bit with my fingers on the back (thus unscrewing the nut about 10 degrees). I then rotated it back to get another 10 degrees of slack, wedged the nut again with my screwdriver, and rotated the back again. After 30 or 40 repetitions of this, I was able to get the nut off of the shaft, push the whole switch back into the dash, and then snake it out of the 'Select Drive' hole.
2) Testing the ground lead:
Since another poster had said that my symptom (only one switch position worked) could be caused by the ground lead on the switch being disconnected, I tested that by jumpering the ground lead directly to the Eagle's body. No luck...
3) Repairing the switch:
I unplugged the 7-pin connector, but had to cut the ground lead because I couldn't find any way to unplug it from the switch. I was careful to cut it as close to the switch as possible, so that the stub going into the dash would be long enough for me to fish out and solder to later. Then I removed the switch for repair.
The back half (connector side) of the switch is made of black plastic, whereas the front half (shaft side) is made of gray pot-metal and has 3 tabs that wrap around and hold it to the plastic half. By prying very gingerly with a blade, I was able to lift the tabs enough to separate the two halves of the switch (actually I broke one of the three tabs, but that's why they make JB Weld...).
Once the switch is open, you'll see that the pot-metal side has a flat disk with some copper areas 'mapped' onto it, whereas the plastic side has several brass 'fingers' that reach up and contact the disk as it is turned. These fingers are kinda like the battery connectors on a kid's toy.
To repair the switch, I carefully tugged on each brass finger a little bit to stretch it back out to its original length. Then I got a fingernail file and buffed the tops of the fingers where they contact the copper disk. Finally, I got some isopropyl alcohol and some q-tips and cleaned the accumulated crud out of everything. I pressed the two halves together, and tested all of the switch positions against the continuity chart that is in the Factory Service Manual, and verified that everything now worked. The final step was to re-assemble the switch and JB Weld the halves back together (no, I do NOT plan on ever dissembling it again), and re-install it in the dash.
4) Re-installing the switch.
It was almost harder to replace the retaining nut than it was to remove it, because when I slid it down the shaft to the threaded part, it was impossible to hold it perfectly perpendicular to the threads so I could get it to engage without cross-threading. I ended up replacing the cursed slotted nut with a standard 3/8 fine-thread hex nut that was easier to work with. I got a short piece of 3/4 inch diameter heat-shrinkable tubing and shrunk it around the hex nut to make a handle. I was then able to position it down the dash recess, engage the threads, and tighten the nut down.
The end result was fully functioning wipers: both speeds now work, the blades don't get stuck, and I even have the intermittent function!
Hope this helps somebody out there...
John B.