If the battery cables, especially the ground, are clean and tight at the battery and block, get a new battery. I don't think its being checked properly. Low amperage output causes a slow start.
I've had batteries check at 12.4 volts and only supply 70 amps. Not enough to turn the motor sufficient for a correct start. You'll find with a new battery, it will kick right over.
I've had batteries check at 12.4 volts and only supply 70 amps. Not enough to turn the motor sufficient for a correct start. You'll find with a new battery, it will kick right over.