See if other accessories work (headlights, hazzards, interior light etc) If they work then the batt and cables SHOULD be fine. By your sig you have a 4spd? The solenoid mounted to the inner fender should have a ground connect built in to it. The solenoid needs good ground to your inner fender to work. If someone stuck a automatic solenoid in there, they would have had to run a ground wire from the neutral safety terminal to ground. If that's good, check the + terminal connectors on the solenoid and the starter. Check to make sure the starter is bolted solid to the tranny (I've had one come off). If all that checks out nice and tight, then tap the solenoid and starter with something non metalic (screwdriver handle etc) and see if a little "percussive maintenance" does the trick.
