How long was it between the time you last used the switch when it worked, and the next time you pressed it when it didn't work?
Switches do break (if not the switch itself, then the solder contacts on the logic board) and contacts do oxidize over the years. You need to carefully open your Mac and check the switch on the logic board itself. And I personally would love to see some crisp, zoomed-in photos of your switch when you do that (both top and bottom of motherboard).

Click to expand...

I've been using the switch regularly (like a couple times every week, mostly because of Netscape 2.0.2 hanging now and then). So I immediately noticed when the switch stopped working.

Initially I suspected the switch itself. I desoldered it, measured the resistance across the pins of the switch, and across the grommets on the motherboard where the switch sits. Then I soldered the switch back in place. No improvement.

I'm pretty confident the switch itself works fine.

Here's a summary of my ohmmeter tests:

* Reset switch (location S1 on motherboard):

- Switch mounted on board, pin-to-pin, button unpressed: 0.625 kOhms

- Switch mounted on board, pin-to-pin, button pressed: ~1 Ohm

- Switch desoldered off the board, pin-to-pin, button unpressed: infinite kOhms

- Switch desoldered off the board, pin-to-pin, button pressed: ~1 Ohm

- S1 grommet-to-grommet (switch removed) on board: 0.625 kOhms

* Programmer switch (location S2 on motherboard):

- Switch mounted on board, pin-to-pin, button unpressed: 1.425 kOhms

- Switch mounted on board, pin-to-pin, button pressed: ~1 Ohm

By the way the Programmer switch responds perfectly fine at all times.

Anybody care to check their values on their motherboard with a working reset switch? Let me know. It might help me locate the problem (open circuit hypothesis).

Next, I'm going to look real close for a broken trace on the motherboard and check the capacitors.