the magnet is very small, and has a little plastic retainer "cage" that holds it in the cam gear. The magnet part number is AC-Delco 25530386. It runs about $16 at a Delco retailer, or about $22 at the dealer. It doesn't sound like this is your issue though with the other electrical gremlins you're having. I would inspect the ECM for water intrusion damage since it's mounted under the hood and exposed to the elements. It's under a cover in the passenger side fenderwell between the wheel well and passenger side headlamp.