On the master contactor, if the studs on the have turned at all they won't be making positive contact. And it might work under some loads.  Replace the contactor, it's a $20 item.
On the low voltage, I have seen the connection point on the back of the red split switch become loose enough to create a resistance to give a false voltage at the sense line. Replace the switch or stake the tabs on the back of the switch down. Also make sure the connection is good at the terminals. These could get loose over time ( or if removed and reset a couple times ) if they are the the stab on type or just loose screws.

---

Get the power of Windows + Web with the new Windows Live. Get it now!