Introduction
As noted in the section on Common Problems and Fixes, the power seat controls are a frequent failure item on the Classic. Because of their horizontal position the intake of dirt is facilitated, eventually causing the contacts to cease conducting. The official solution is to replace the switches with new ones (for about $120 each plus labor).  Later models (and new replacement switches) have a rubber membrane under the control knob openings to prevent the ingress of dirt that causes the problem.

Alternatively, you can save a few dollars by taking the switch apart and cleaning the contacts with a contact cleaner pen (Radio Shack and most other electronics stores sell them). A quicker temporary fix is to pop the top off the switch housing and squirt spray-type contact cleaner (also available at Radio Shack etc) into the switch. Below are detailed instructions for these operations, contributed by Kevin Kelly and augmented by my own experiences. The photos were contributed by Alexander Cooper. When you take one apart you will realize why a new one costs over $100! Care is needed in disassembly, or springs and ball bearings explode everywhere.

Tools Needed
Small regular screwdrivers, medium Phillips screwdriver, larger Phillips screwdriver (for screws attaching switch to case),  needle nose pliers or big tweezers, and heavy grease. You also need a good quality contact cleaner pen (or contact cleaner spray if you want to try the quick fix). These are both available from Radio Shack and other electronics stores. Trevor Easton recommends Stabilant 22 contact enhancer -- "a magic concoction from Canada for repairing recalcitrant contacts in switches, plugs, sockets etc".

Step By Step Procedure
1. Put the driver's seat all the way forward and check the two 30 amp fuses under a black plastic cover to make sure this is not the problem. Also make sure the fuses are getting power. Remove the fuses or disconnect the battery for safety (if the latter, make sure you have the radio code).

2. Pry the black plastic seat control knobs off with a small screwdriver. On the knob for the back, pry at about "shoulder" level; for the knob for the seat, pry just off center.   Insert a screwdriver into one of the two slots on the seat side of the switch housing lid, and twist to pop the lid off the switch housing.  The clips holding the lid on are plastic, so just use enough pressure to get the lid off. (Nothing will explode just yet).
 

Seat switch housing with knobs removed.

Lid removed from housing.  The two screws that need to be undone are in the top left and bottom right corners.

3. Sometimes you can get the seat working at this stage by spraying contact cleaner through a tube into the openings on the switch, avoiding further disassembly. This will not clean the contacts as well as a contact cleaner pen with the switch apart, but it may get the seat to move enough so you can drive the vehicle. (Remember to replace the fuses to test the switch). Otherwise, continue as below...

4. Using a Phillips screwdriver, take out the two screws holding the switch to the housing. A magnetized screwdriver will help to avoid them falling down into the housing, but if they do, you can easily retrieve them later. Lift/Pull/Pry the switch out of the housing.  The wires that are attached to the switch are not very long, so you may need to ease the wires into the housing from under the seat.  Disconnect the connectors from the switch assembly (You can push the plug out of the switch with a regular screwdriver). Take the switch to a well-lit workbench.
 

Switch housing after switch removal, showing the two connectors and wiring

Switch removed from housing

5. This is another opportunity to try the spraying in of contact cleaner without further disassembly -- you can check the contacts with an ohmeter to see if they are working after spraying and working the switch. If not, disassemble the actual switch as below....

6. Take out the screw from the bottom of the switch. Turn the switch so its top (the switch posts) is facing up. The top cover of the switch is held by 5 clips which are integral with the cover: two on the seat side and one on each of the other sides.  Using a small screwdriver as a vertical wedge, release each of the clips in turn. *DO NOT disturb the posts*. *This is the trick part*. SLOWLY lift the cover, and keep an eye out for any ball bearings that may roll out on to the bench. (Trevor Easton suggests doing this disassembly in a large plastic bowl so you will catch anything that falls out).
 

Underside of switch showing connector pins and screw that has to be removed.

Switch with top cover removed, showing the balls above the 8 contacts.

7. With the top off the switch you will see all the round contact points.  Lift off the BB's on the top of the springs with the pliers/tweezers, lift the springs out of the holes, lift the plastic rocker out (noting how it went), and lift off the BB's from the bottom of the springs.

8. You can now lift out the two brass contacts from each contact pair to clean them with the contact cleaner pen (I like to clean them one at a time). While only one contact may not work, you may as well clean all of them, while you have the switch apart.
 

Disassembled Switch. The back and forth post can't be removed easily but the contact pieces can be slipped out from under it.

Switch partially reassembled

9. As they always say in shop manuals "reassemble the reverse of above"  Put some grease on each upper ball bearing before putting the top cover on the switch.

After you have accomplished this operation once and get into training, you might be able to do it in half an hour per switch!

Note for "Advanced Switch Repairers"
Alexander Cooper reports that after doing this operation a few times he no longer bothers trying to keep all the balls and bits and pieces in place during disassembly. Once you know how it all fits together, it is not critical to see where all the bits came from, so he just lets them fall out and catches them. Alexander has also had good luck doing the reassembly without grease -- omitting it so there is no chance of it attracting dirt.