Single blade decks are not adjustable side to side.
Thank you, Rivets for that quick reply, I really appreciate it. At least now I'll stop making myself crazy trying to figure out where the adjustment is.
While mowing I got careless and allowed the blade to hit a tree root *hard*. This is my first riding mower & I was upset enough when it happened that I put it away & finished the lawn with my old walk-behind mower. Later, I ordered a new blade, changed out the old one, and gave it a try. The mowed grass was clearly uneven, it looked like hell, and the tractor sounded like it too. I stopped after a minute or two, put the tractor away & have been mowing with my old walk-behind mower ever since (which sucks).
Reagrding the blade angles, I bought one of those little blade-height-measuring tools I've read about on this forum (and which is super-handy btw), and the blade is correct front-to-back. From side to side, however, the left side of the blade hangs a full inch lower than the right side. I made sure the tire pressures are the same on each side and have rotated the blade 180-degrees and measured again and each time I get the same result: the left side is 1 inch lower than the right. I also noticed the blade is hard to turn & I hear a scraping sound although the blade is not making contact with the edges of the deck at any point. Which could point to the spindle, maybe?
I haven't removed the deck from the mower yet, mostly because I haven't done it before & feel a little intimidated. At the same time, it would be a good way to learn more about this little tractor & I probably should just bite the bullet & do it this weekend.
I suppose the impact with the root bent a frame mount. If so I hope I can bend it back. If you or anyone else have any other ideas on what to check or how I can fix this, I'd be extremely grateful to give them a try. Thank you!