I got in one morn, cranked it over, it began to start, I let up on the key
and now it'll just crank, crank, crank with NO hint of starting.

TIA for any help.

Any history to this?

It takes fuel and spark to make a motor run. One of these is missing,
your task is to determine which is needed.

Remove a spark plug to see if it's wet with fuel -- or not. If dry, I
suspect the fuel pump relay or fuel pump itself is bad (or the tank is
dry). I'd discount a dirty fuel filter for it would let some gas
through, at least enough to briefly start the motor. Check the battery
connections to be sure they're tight and all wires (to fuel pump) are
connected.

If wet, the spark is missing because there's a fault somewhere in the
ignition system, including ignition switch.

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© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

I would suspect the overload relay first... very common problem.