I digress. The Planet continues to Evolve as it always has. The Ice Age was only 15,000 years ago. Climate change is real but only a tiny percentage is caused by mankind. WE didn't start it and we Cannot stop it. A volcano emits as much crap in an eruption as we do in a Year. Learn to live...
A 21 or 22" will suit you well. You can often find suitable and reconditioned older mowers for $200 or less. Skip the Mulcher/bagger types.
1/3 acre ( 14,520 square Feet) minus home/garage, laneway, trees etc isn't much to mow. Older 3+HP Briggs and Stratton powered (not the newer Chinese...
Only mow when grass is Tinder Dry. After changing the oil, I remove my Deck in the Fall and turn it upside down on a gravel area and pour the used oil into it, swabbing it on all sides and protruberances. Leave it overnite to soak into rusted areas.
I believe at least 2 of the Flat Idler pulleys are loose and need replacement .
Put the front deck control arm back where it was and loosen off the Nut to replace it. Level the deck with front 1/8" lower than rear. Belt appears OK.