I am so confused by the OP. I just don't think he understands what the springs are supposed to do in a seat. The springs are nothing at all like the springs in a car's suspension. They are not there to make the ride cushy or fluffy, not their intended purpose so there isn't anything to fix.

So you can't fix a seat to make it a suspension seat, there really isn't such a thing. If you really want a bike to be cushy, you will need to put some sort of suspension on the bike which probably means a suspension seat post (best idea) and maybe front shocks.

As far as I can tell, the springs in most seats are there to absorb severe shocks, like when you fall off of a pot hole or hit a curb or something like that. Heck, I am 380 pounds and have found them to be useless and removed them and put normal "skinny guy" seats on my bike and don't notice any less cushy of a ride.