997 forward pressure spring broken

Just got a used pair of all-metal 997s, but I noticed that the forward pressure spring on one of the heelpieces is very weak. Normally it should take a lot of force to slide the heelpiece backwards on the track against the spring, but on one of these I can push it with just one finger! With the boot clipped into the bindings, I can push the boot backwards far enough by hand to make it release (haven't skied them yet though).

So, does anyone know how to repair/replace the forward pressure spring? I don't even know how to remove the heelpiece from the track on these, the forward position adjusts by a screw rather than a lift-tab like most sollys.

Alternatively, anybody have just 1 good metal 997 heelpiece they'd be willing to part with?