Replying to FKS 155 Problem...

alright, so i have the older gold/black 155's mounted on my jibs.  Both my DIN and FP are absolutely set right, but about 4 out of 5 times i land switch on jumps, one of my skis ejects.  The only weird part is, instead of the normal release where the heelpiece stays clicked up, the heel piece pops down so the binding actually unclicks on the landing, even if i stomp my landing real clean.  My guess to this problem is that maybe since the bindings are so old, a spring or something is too worn or exhausted and thats why im unclicking.  Any other suggestions before i go to a shop for a release test?