OK, so an update.

As per my other post, I had some issues with the flywheel. I believe these issues were what was causing the pull starter to slow and become difficult to pull.

Also, I added the plate to the starter, under the pulley, to stop the spring catching. I haven't fired it all up yet, but so far so good...ish.

I found when testing it dry, the pull start will rotate all the way if pulled slowly. However, if I pull the pull starter too quickly, it locks up and completely stops moving, almost like a car seat belt, OK when slow, locks when fast.

Has anyone experienced that or does anyone have any ideas as to what might be happening?

I'll test the mower when it's not 3 AM and let you all know how it goes.

Cheers!