An impact wrench would be helpful. Or you could try tightening the blade extra tight. Is there parts of the spindle shaft exposed anywhere? Long enough threads so you can lock 2 blade nuts together? Not familiar w/ your mower.

Thanks - I'm debating investing in an impact wrench to get the pulley nut off, as I'm running out of other ideas. The issue then is trying to hold the pulley. which will spin when I try taking off the nut above it. Any ideas on how to hold the pulley? I've looked around online and come across an Irwin vise grip chain wrench. Anyone ever use one of these?

I've tried to tighten the blade extra tight as suggested, but it seems to put even more tension on the pulley nut, because you have to hold that to tighten the blade bolt. I've also tried locking two nuts, but they loosen as I increase the tension on the pulley nut I'm trying to remove.

The "chain wrench" will damage the pulley! so order a
new 1 . may be a last resort.
later,,,codger (al )

spray the nut and top of spindle with PB Blaster and let set 15/20 min and then try to loosen nut. and yes an inpact wrench with help as well, but just try the blaster first.

"- I'm debating investing in an impact wrench to get the pulley nut off,"

Good excuse for getting one which will be helpful from now on. I hate to admit it but mine is just a cheap, probably Taiwan job and I have used it for years fairly often, now would be Chinese. I'd try Harbor Freight.

Walt Conner