There is a metal bar across the back of the bridge on which the strings attach. On this metal bar, there are 3 holes, one the whammy bar sits into, the other two are where the spring adjusters are, Just use a hex (allen) wrench to adjust em by sticking em in the hole.
Also, if you Really want high spring tension, take the bottom plate off, and there will be 2 notches on the pivot screws, move the springs up a notch for more tension.
