The clutch must be somewhat rusted to the shaft. Normally the clutch has a heavy washer like flange on the bottom that would retain the key if a separate key was used. Does the clutch look damaged to you or does the original bolt appear to be broken in the crank? If all it looks like to you is that the key is out, maybe it could be driven back up if the clutch is siezed to the shaft. The upper pulley may need to be spun to align the keyway. BTW, the key shows as 1/4 x 2.5" long and the bolt is 7/16 x 3.25 long (20TPI) I'd think a grade 5 or 8 along w/ a lock and thick flat washer. Otherwise a touch of well placed penetrant on top the clutch and time you may be able to carefully extract the clutch.

Thanks for responding. The bolt and washer that holds the electric clutch on is missing. Nothing wrong with the threads in the crank. There appears to be no rust on the shaft/clutch. Today i tried driving the key back in, but it wouldn't move. I didn't try to force it. I also sprayed plenty of PB Blaster above the clutch and pulley. Going to let it soak until tomorrow. I would guess there is about 3/4 inch of key that is visable. I did get it started today and you can see the shaft is spinning in the top pulley, so the key has dropped at least that far. The shaft may be beyond repair. May try to get a puller on the clutch tomorrow. It's a Vangard engine, hope i can salvage it. Thanks again.

Glad the rest looks ok. Those really were nice riders with the Vangard and the Eaton transaxle. PTO clutches don't really like to be pulled on. If the slot in the above pulley could be located by tapping the key up gently whilst either turning the drive pulley or shaft slowly- that would be a better bet. I've been down that road before in trying to extract a clutch without damaging. Sometimes every trick in the book gets you nowhere. Patience and a touch of penetrating oil is the best bet. Had one that I didn't think would release that I pulled the engine bolts, lifted the machine slightly off the ground via the engine straps and with some help w/ an air chisel- the clutch had worked its way off. Risky yes, but it worked out. Pricing the clutch will help with the patience factor!

Got the clutch and top pulley off. I took the bolts out holding the engine, cut three tapered wedges from 2x4s drove them between the frame and engine a little at a time and the clutch and key fell off. The top pulley had spun on the shaft, but i think i can take a file and true the keyway up. The clutch doesen't look damaged. I have an identical mower that i bought new in the early 90s before Troy went out of business. It is a good mower. Won't know if the drive system on the freebie is any good until i get it back together. Thanks again for your help.

Make sure the flywheel key is aluminum. A steel key won't give the same protection as an aluminum one. (I think they are aluminum--could be mistaken, altho B&S and Tecumseh keys were.

Good idea on the wedges you made. Glad it's apart. I'd use some blue loctite on the bolt when it goes back together, clean up the shaft + coat it w/ anti seize. Look over the locator rod for the clutch to see that it is solid yet. I say that as one summer I put two clutches on these for that locator letting go and the wiring tore out of that nicely priced clutch! Think heavy duty flat washer too.

I was able to get the keyway and engine shaft cleaned up with a file and emeroy cloth. Replaced the lower crank seal while i was at it. Put everything back together. I used Loctite as was suggested and anti-seize compound. I will have to clean the fuel system, replace fuel lines and filter, change the hydro oil and filter, and air the tires up, before i know how everything works. Also will remove the engine shroud and check for derbis/mice dens. Should end up with another decent tractor. Not sure what the deck will need yet, a belt for sure, and maybe new blades. Thanks again for your advice. For what it's worth, long ago i took a spare plastic fuel tank and mounted it up high on a pressure washer cart, added a long fuel line and shut off valve. I use this to start and run engines that have not been run in awhile.That way i know i've got fresh fuel at the carb.

Good idea on your "test fuel tank".
I just want to remind folks that if ever you have the need to run an air cooled engine with the fan shroud removed.........the cylinder and head can overheat if you run the engine for more than about a minute like that.
Without the shroud to duct the fan air to the engine parts they will not be cooled.

After removing the engine shroud, there was a huge mice/mouse nest packed into every crevice. With a metal coat hanger and air compressor i was able to clean it out. If i had run the engine for any length of time i'm sure it would have overheated and ruined. Everything is serviced, runs good. Will leave the deck off til spring and use the tractor this winter for around the house jobs. I have quite a few limbs to saw up from storm damage. Will use the tractor to tow my cart. By the way, the old fuel lines, you could snap like a twig they were so brittle. Thanks again for the advice.