The seat adjuster handle is twisted or the seat adjuster handle is bent.

Straighten the handle in order to ensure that both sides release and lock at the same time.

Or, replace the seat adjuster handle.

The adjuster lockbar return spring is broken.

Install a new adjuster.

The lock sticks or the lock binds on the adjuster.

Lubricate the lockbar pivot.

If the lockbar is binding, eliminate the cause of the binding or replace the adjuster.

The cross-wire is bent or the cross-wire is hung up.

Route the cross-wire correctly or replace the cross-wire.

There is an obstruction or the lockbar is bent.

Clear the obstruction or replace the lockbar.

The cross-wire is missing or the cross-wire is disconnected.

Connect or replace the cross-wire.