start with the obvious,check the battery to make sure it is good, clean and
tighten all connections.Get rid of the wing nut on the ground cable.Check
the voltage at the starter especially when cranking.If you have a dash mounted
volt gauge watch to see where it drops at crank(ing speed.If all that is good
then i would check starter.Bendix could be bad,dirty or it could be the starter is
worn out and just not spinning fast enough to engage it.
personally i like to put the engine cables on the studs alone then i use
these adapters for the small wires.I don't use wing nuts on anything.
http://www.midlandhardware.com/15857...Fci1wAodaRkP9w