Recently, when it "acted up" and wouldn't start with key, I grabbed multimeter, had my wife turn key and I read out 12.1 volts. I read at S terminal also which at that time was 9.9. Jumpered the starter so I could drive to work. Then later at work, when it would start with key, read it out again and had 12.1 volts. I used battery ground cable at engine block for a ground and also the ground at the coil.
