The adjusters are misaligned.

Align the adjusters.

The adjusters are new, not broken in.

Operate the seat to the fully forward and fully rearward positions several times in order to work the tightness out of the channels.

The adjusters are improperly lubricated.

Lubricate the adjuster channels.

The adjusters are bent or damaged.

Replace the adjusters.

The adjusters are binding or damaged.

Lubricate or replace the adjusters.

The seat components are loose, damaged, or broken.

Repair or replace the seat.

The seat mounting bolts are loose.

Tighten the mounting bolts to specifications. Refer to Fastener Tightening Specifications .