Someone will correct me if I'm wrong, but the piece you are talking about is the damper. It doesn't return by itself. That's the job of the spring.
Not to be too critical, but if you've got the original 30+ year olds shocks, then it's time to get some new ones. The $80 shocks from partsnmore.com perform better than the originals. It only goes up from there in price. All depends on your budget and timing.
cheers, Joe