Weak starter, weak battery (or both), tight engine. Those are your choices.
Now you need a strategy to figure out which of these is the culprit.
Is your battery 6 volt or 12 volt? If it is 6 volt, turn off everything electrical and power the starter with a fresh 12 volt battery to see if it turns over. 12 volts won't hurt a good 6 volt starter.
If the 12 volt battery turns the engine over, take your 6 volt battery to someone who knows how to load test it.
If none of this works, you probably have a tight engine. You can start a 216 with a hand crank. They came with one new.
