If you can jigle it it must be already loose. If it isn't loose, there is a problem with the conector or the wires, moving wires arond shouldn't alter the idle if they are solid. To adjust you need to find and loosen the two screws, and if you don't have an ohm meter you adjust by feel. Turn the switch counter clock wise 'till it stops, then as you turn clockwise, you will hear/feel a click like a microswitch would do. That is where you stop and tighten the screws. If you have the Ohm meter, follow Bentley's advice.