For 1990-2009 cars

Problem | Action
--- | ---
The adjusters are new and not broken in. | Operate the seat to full-forward and full rearward positions several times. This will work the new tightness out of the channels.
The adjusters are improperly lubricated. | Lubricate the adjuster channels using Lubriplate Auto-Lube A or an equivalent.
The adjusters bind due to being bent or from damaged channels. | Replace the adjuster.
The adjusters are not in parallel alignment with each other. | Loosen the floor pan attaching bolts or nuts. Align the adjusters so that the adjusters are parallel on the floor pan. Retighten the nuts.