P200E won't start + flywheel comes off - Please help me specialists

Hi guys,

PLEASE help me with this one, I’m a beginner but anxious to learn!!

What did I do:

-opened up the cylinder to inspect the piston and rings, these are ok and shiny so no blowback
-Removed the flywheel, the half-moon key has got stuck between the flywheel slot, is deformed and so is the crank slot, but I’ve replaced the half-moon key with a fresh one and there was’nt any real damage to the crank.
-I Put back the flywheel, but couldn’t get it tightened properly, are there any tips/tricks to this?
 the flywheel keeps coming loose, very bad thing!!

Now what’s wrong:

-The vespa won’t start after 1st kick as it used to, instead it does 1 stroke, stalls, and it doesn’t react well to giving gas.
-Eventually it will start, but only when playing massively with the choke.

PLEASE HELP

Yes it’s the original one, but this topic can be closed, I bought a shiny new PX200 engine
from scootermarket, so I put my GS200 engine on ebay.be

Check it if you’re interested.

Thanks for your replies, people!

Woodruf key is smashed, crank is smoked and it’s gonna cost me 500€

Now I’m in trouble

Is it the original flywheel?