"the rear seems just fine but the front isn't springing properly... maybe the curvy metal thing needs to be bent out??
How are the bearings? those brakes are designed to work without the fork pins, hence you can't really adjust the spring tension on them significantly (unlike regular V-brakes where you can adjust them by turning in the tension screws or using a more aggressive pin engagement on the fork or rear mounts). Because of that the friction in the system needs to be extremely low. Yesterday I took apart a set of those that I got off evilbay and they were caked in dirt and some of the bearings feel notchy. I had to make a custom 4-pin spanner in order to dismantle them to the last bolt (you'll need that for the bearing holding tube that has 4 notches, do NOT try to use some other tool that doesn't quite fit for you will destroy the notches in the process, they're kinda tight on there and you need to be able to exert full torque on them). Long story short... after taking the brakes apart till the last screw, I was able to clean the bushing setup in the parallel push system and put a couple drips of oil on them, it made a huge difference in how smooth the system operates. I still have to buy new bearings and press the old ones out in order to have those work like new. I'm looking at the system right now and I don't see any way to increase the spring tension, hence the only other way to improve the system is reduce friction (a good cleaning and new bearings go a long way on that).
The hand adjuster knob in the center of the arch seems to be used for side-to side brake pad to rim adjustment. The amount of engineering that went into those brakes is amazing (same goes for the levers, not very flashy looking but most impressive in the details). I can try to post some pictures of the dismantling process (since I have to do it again when I get the new bearings) hope that might help.