I would remove door panel, disconnect wires to motor, connect headlamp bulb to substitute for typical motor load. Now try your switch...does bulb light every time you press the switch (up or down)? If Down works good but Up is flakey....you have a bad switch.
Bill: OR, loose or misaligned track, or weak overheated motor or loose screw , etc. . I know you will figure it out as soon as you do as Dan says. It is pretty intuitive.
You can put 12 volts directly to the motor when the door panel is off to determine if it is switch or motor or whatever. My best guess is the motor. If so, you may need to buy the motor and regulator assy together. Can be tricky to R & R but very doable. Have band-aids ready, lots of sharp metal in there.
Please post the schematics. I would like to trouble-shoot this without taking off the door panel to do basic "reverse engineering". My experience is that there are plastic tabs/clips holding the panel (and lock rods) that are prone to breaking if I go in there. I had an older Chevy that had the switches controlling a module/relay for the window "system", not controlling the motors directly; this may be similar.
Close to a 1994 Olds SUV, drivers switch panel, loaded with bare copper contacts, turned brown, copper oxide, good insulator. Took everything apart and polished all the contacts, need a clean workspace with plenty of space and have to watch out for springs flying all over.
Not as bad, only two rocker switches, are interlocked because they power an reverse the polarity to the motor. If they weren't interlocked, if the driver decides to close the passenger window and the passenger wants to open it, would be applying opposite sides of the battery to the same motor, shorting out the battery.
See rockauto.com sells new switches, if you want to lay out 100 bucks. Had to open the power window switches on my 92 DeVille, was curious why they were trouble free, used all tungsten contacts like in old ignition points. EPA banned electroplating in the US in the late 80's, so we got stuck with bare copper switches. Ford and GM were notorious for this.
Never ever had problems with manual windows, even base model vehicles come with power windows, but no cruise control. Moon roofs use to come with a crank if power fails, but also history.
Got stuck 300 miles from home in a major thunder storm, had to lower the window for a toll booth. Was easy to repair that, but not to remove the entire interior to dry it out.
Always think twice before lowering a window.
My 88 Supra passenger side window would not go up, guess after 30 years, what should be a normally closed contact on the drivers side wasn't quite making contact, and thank goodness, sun was out, 20 miles from home. Switch assemblies could be popped out and disconnected from a connector. Just took the drivers switch out, opened it and burnished the contacts. But can also be on the passenger side, so also removed that to burnished the contacts.
Was working back in the 60's with Bell Labs to develop all solid state switching and touch tone dialing. Had huge rooms with thousands of relays and stepping switches. That's when I learned I learned about burnishing switch contacts. Had crews working around the clock cleaning contacts, solid state laid off thousands of them saving Bell and other phone companies millions of dollars. So what did they do? Increase the rates for touch tone by ten bucks a month. Now getting screwed blue by cell phone companies.
Bill: Yes, I think that with the diagram you can jump wires at the switch area and find out if the motor is working properly or not. I have done that procedure before and discovered it was the motor-regulator assy. , not the switch. Good luck.
Can't believe that low level surface mount circuit is part of that power switch, never seen a circuit like that before in a power window switch, but always a first time, and as usual that 8 pin IC has an OEM number on so can't repair it.