The drivers seat will not recline, the seat still moves back and forth

Move back and forth the black lever. Put some downpressure on seat. Sounds like the spring is stuck and wont disengage.

It's a power seat or manual?

You must remove the motor, move the seat to the desired position and then reinstall the motor to lock the seat in the position.

Mark, try moving the seat back itself, rocking it back and forth whilst operating the tilt lever, you may need an extra hand

The switch itself most likely faulty.

Probablyt because the little wire cable that activates the release mechanisms on both sliders is broken, and therefor only allowing only one slider to release when you activate the seat adjusting lever, and leaving the other one engaged, preventing you from moving your seat. This is relatively easy to diagnose, if you know what to look for... Just try to see what all moves when you press your lever. See if there is a wire cable that is activated anywhere under your seat it should be relativley close to your lever and run across the open space to the opposite slider.

On W-Body vehicles, the front seats are secured to the floorpan by two front hook attachments and two rear bolts installed to nuts welded to the floorpan.
The manually operated two-way front adjusters provides only fore and aft movement of the seat. When the seat adjuster handle located on the front seat is pulled up, the seat adjusters unlock, permitting travel of the seat. When the seat is in the desired position and the seat adjuster handle is released, the seat locks in place.
A power operated six-way seat adjuster is available. The adjusters are activated by three 12 volt, reversible, permanent magnet motors with a built-in circuit breaker. The motors are energized by a switch bolted on the seat side panel.
The three motors drive the front seat and rear vertical actuators and a horizontal actuator. When the adjusters reach the limit of travel, torque is absorbed through the rubber mounted grommets located between the motor and the support. An overload relay is provided in the circuit and will open should excessive stall be applied.
The optional 60/40 split bench front seats have seat back head restraints on the driver's and passenger's seat back. The head restraints are designed so they cannot be removed from the seat back without first inserting a small rounded tool inside the head restraint support tube to release the locking tab. The 60/40 split bench seat is equipped with a reclining mechanism on both the driver's and passenger's side. The recliner lever is located on the outboard side of the spring cushion. When the lever is pulled upward, the spring loaded dual linear reclining unit located in the cushion frame is released, allowing the seat back to be pushed rearward or allowing the spring loaded reclining unit to bring the seat back forward.
Bucket seats are equipped with manual reclining mechanisms. An optional six-way power seat adjuster is available. Some bucket seats are equipped with inertia seat back locks. This system allows the seat back to fold forward without requiring the occupant to release a locking lever or access to the rear seat area. During a sudden stop or deceleration, or if the front of the vehicle is nose down, the inertia system of the seat back lock will engage, holding the seat back in its rest position. A release lever is provided to allow manual release of the seat back lock when the vehicle is in the nose down position. The release lever is located at the lower rear outboard corner of the seat back.
Some W-Body vehicles (notably Pontiac coupes) have passenger front seats equipped with an E-Z Entry device. This is actuated, in an unoccupied seat, by completely folding the seat back forward disengaging the adjuster, and sliding the front seat forward to gain access to the rear seat area. To return the seat to its normal position, return the seat back to its rest position, and slide the entire seat rearward, engaging the adjuster.
W-Body rear seats are available in several styles including a rear seat with an integral child restraint device.

Yes... you have to push the electrical connector off the motor, and test whether there's 12 V across the pins when you operate the switch. But it really isn't TOO difficult to remove the seat. There are pop-off covers front and back, and you unscrew the 4 bolts. Take out the left middle seat, left the front seat carefully and disconnect the main connector. Then lay the front seat over and reconnect that main connector (use pliers if needed to unclip the socket from the body). Like I say, if there's 12 V there, your motor's no good! If no 12 V, then you'll have to troubleshoot the switch and harness. But I think the motor's kaputt, sorry!

You can move the drivers seat back by turning on the power, getting in the seat and position your feet firmly on the fron flor with your back firmly against he seatback, and then engage the switch pushing back - while pushing like hell with your feet. You can actually hear the seat drive shaft turning while the seat moves back. The principle should be the same for moving forward, but pressure would have to be aplide to the back of the seat.

Use some penetrating lubricant on all pivot points and levers around the recline mechanism, and let the lubricant sit overnight. In the morning, try to work the recline mechanism free. (The vehicle is quite old at this point, and likely parts in the interior need lubrication. These parts should be lubricated annually.)