Front bench seat adjuster not working

I have a 71 Dart Swinger with the lovely front bench seat. I'm 6'1 and I'd really really like to get the seat adjusted as far back as I can.

When I pull on the adjuster I can get the driver's side track moving, but the passenger side isn't releasing. I reached under the seat and found a wire heading to the passenger side, and I pulled on it to try and get it to to release, but really couldn't tell if it was moving anything on that side. It felt extremely slack, but still attached to something. Is there a mid-point pivot or something that holds it under tension? None of the manuals I've looked at has any great detail on the adjuster.

I haven't gotten to the point of pulling the bolts for the front seat yet... I'll need a helper for the weight.

Thanks!

-Daniel