Replying to FKS Release Issues

So I got some FKS 155s of a fellow NSer and have never ridden the bindings before so I don't know if there working correctly or not.

Now its probably a total retard question but the heelpeices are super stiff to release, like if I stand on them and push down they kinda snap back up etc.

When they got mounted and I adjusted the DINs the springs were super stiff. Just wondering if this is normal as I have never ridden/worked on the bindings before, I'm used to Solly/Tyrolia. I have to push pretty hard for them to go down.

I love the bindings and I love the retention just they have never released on me (heels anyway) and was just wondering if its normal or there kinda beat.