majiggy or a doohikky or a whatchamakallit?

Really, I don't think anyone is responding to your thread because we don't understand what you're talking about with such vague terms. It's up to our imagination here.

I can take a guess and you can tell me if I'm wrong or not:
1. Your dash lights are out while driving at night even with your headlights on?
2. You suspect it's the little dimmer switch or dial (on a S70 it's a round dial...maybe on yours it's not a dial but a sliding controller) on your dash that is next to the fog light switch? Thought on the 850's it was above the headlight switch next to the left vent...oh well. Oh, it could be as simple as a blown fuse...did you think of that?
3. You want to know how to take this out to replace...thus you are asking about a "crow bar?"

If the above is correct, then here we go.
1. Yes, it could be the dimmer switch/dial next to your foglight switch, or rather above the headlight switch. (my diagram shows the fogs lights on the right side of the steering wheel...oh well a little different on different cars).
2. You don't need a crowbar...I would try a butter knife...something that isn't going to mess up the area around this switch and isn't too sharp to damage the insides. It should pop right out if pried from the top. Once out, it should unplug easily and a new one plugged up and popped back in.

By the way, if this is what you're talking about then the part number you need is: 9162467

Hope this helps. If I was completely off, then please post back without the doohickies, whatchamacallits, etc. and try to be more exact. We do want to try to help you. Also keep in mind that a blown fuse could be the culprit to your problems and not a bad rheostat. Check fuses 3, 15 and 35 (if blown it will probably be #35). All of these fuses are 10 Amp fuses by the way. You should have a few extra fuses in the fuse box...whatever you do, make sure you use the right one (color coded). Good luck!

Regards,
MIJ

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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon