Over the winter I pulled the dash out of my '69 to tidy up some of the work that was done during the actual restoration. Lights, etc, that didn't work before now work, but I cannot get the wipers, which were fine before, to come on. I've checked override switch under the dash and also under the hood--all good. Nothing under the hood was touched so I know it has to be under the dash. Fuse good, all wiring double checked. The only thing I haven't done is replace the relay. Ground wire missed somewhere?? Wire from ignition switch??? Help! I'm pulling my hair out, and I don't have that much to spare! Thanks in advance for any clues.

The most likely suspect is that you didn't get the wiper switch screwed back on completely, or the panel is loose. The wiper switch itself has to be grounded for the wipers to work. The switch screws into the metal trim panel, and then that screws into metal tabs on the dash. If any of those screws are not making proper contact, the wipers won't work. A lot of guys run a separate ground wire up to the switch, and put it between the switch and the trim panel, with the screw holding it all together. That way the switch will have a good ground.
Since you said you checked the over-ride switch, then I have to suspect the wiper switch is not grounded.

OK thanks I will check that and let you know.

OK tried that. Still nothing. sigh...

Did you unplug the wiper switch (remove the center stack)? When you plugged it in, is it possible that one of the three wires going to the switch got pushed out of the back of the switch, and isn't making contact any more? The terminal ends have a small barb on them that hold hem into the plastic plug housings. They can become bent over time and get pushed out.

Still pulling my hair out on this. Did I miss a ground or something? I also had steering column apart during this project. Could that have something to do with it? Turn signals, etc all work OK.

It may be a problem with the limit switch, under the wiper door outside, but why would that just stop working, if you were only working on the interior?
It's possible you loosened a connection under the dash while working on the column. Do you have a wiring diagram for the car? If not, I can send you one. I may also have some info on the wiper system, as far as how it works, and the components involved.

Check to see if you have electric at the wiper motor using a voltmeter. If you have electric, then make sure the wiper door is raised up high enough to make contact with the relay. Make you checks with the engine running. Vacuum is a haunting nightmare.

I've had this problem before.  There is a vacuum switch on the back of the tachometer (or maybe its the speedo) that you may have hooked back up wrong or didn't get the vacuum lines right.  It's a PITA to get to as you have to pull the speedo/tach panel out to get to it.

http://www.parts123.com/parts123/yb.dll?parta~dyndetail~Z5Z5Z50000036b~Z5Z5Z5AACRS~P79.95~~~~S3RG0RK7LT96226114924G~Z5Z5Z5~Z5Z5Z50000036b

My wipers quit working last year one day. Turned out to be a loose connection at the wiper motor. Took it apart, cleaned it and away it went. Worth a try.