From memory there are 2 or 3 terminals with 8mm bolts, remove them and clean the terminals with sandpaper/dremel whatever you've got. I've had the bolts snap off before though, so I drilled new holes alongside, and used those 10mm headed self-tapping bolts to secure the terminals. If the terminals are really bad you'll need to replace them.

You're on the right track wIth the PATS light.