I had to remove the LH engine cover to get at the wiring where the drive pulley had rubbed through one of the stator wires. That went fine. I repaired the wire, and put it back together. Now the starter won't turn over the engine. The starter clutch is fine. The idler gears are fine. I can hear the decomp clicking when I push the starter button. Removed the side cover again and took off the spark plug wire. With the engine cover off, it'll turn the engine over just fine. As soon as I put the cover back on, nothing except the starter wire gets hot if you keep trying.  I don't understand what the cover could be doing, since I can turn the engine with a wrench on the crankshaft bolt through the view port for servicing the valves. WTF?

When you install one or both of the washers on the idler gear, the system gets locked up when you reinstall the alternator cover.  The starter drive incorporates a one-way clutch so when you rotate the crankshaft with a socket all seems normal, but the starter drive gears will be locked up.

It's very common for the outer washer to come off with the cover, then it drops off.  Easy to then put it back on the wrong shaft.  Check your starter drive.  Make sure the two thrust washers are on the over torque clutch, not the idler shaft.

DBM is spot on!  I’ve made the same mistake.  I can’t recall the boss orientation.  I may have a photo.  I’ll check.

Thanks! That was the problem. I've been pulling out my hair for about a month now, over a misplaced washer! (And I don't have hair to lose!) I just had to ask the people who knew! Thanks again!