Keep digging you will figure it out. Just a few ideas on test gear...Insulate the dmm probe with quality electrical tape except for the tip. Beware of how much voltage your subjecting the scope to and scope probes in general. You can be seriously shocked by trimmer access holes, gaps, etc. Buy an isolation transformer and plug the scope into it. Also pick up some desoldering wick before you bust the board traces. Let us know what you discover.