Radiator clean, coolant level good, fan & fan belt good?
You're putting up hay for hours you'll need to blow out the radiator and clean the air filter often.
Gotcha,
2.5 Brake section
2.5.1 Structure of brake system
The mechanical wet disc brakes are used for the travelling brake. The brake is operated by the brake pedal (13) through the mechanical linkages and provide stable braking and require little adjustment. The brake body is incorporated in...
If you don't already have a Workshop Manual here's a link. Has diagrams and descriptions of linkage and how the brake system works and how to adjust.
BX23S WSM.pdf
As North Idaho Wolfman said try to fix the one you have, got nothing to lose if it's already broke.
Found one at German Bliss for a lot less if you can't fix yours.
I'd call them to be sure it matches what you're looking for though.
I would also add a water emulsifier to help disperse any leftover water/condensate in the fuel tank just to be safe. Also a good time to check for any foreign bits in the bottom of the tank while you've got the tank drained.
Have you checked to make sure all the tire pressures are correct?
With the mower on a flat surface are the right and left side heights identical when raised and lowered?
The LX3520HST is spec'd at 1,100 RPM at low idle so you're spot on.
For reference my BX1880 is spec'd at 1,350 to 1,550 at low idle.
Maybe my BX is a bit quieter but it's never bothered me any.
It's just how it is.
I had a slow leak for months that was driving me crazy (I know - short trip 🤪).
Did exactly what you're doing trying to find the leak.
Turned out the valve stem wasn't tight but never showed any bubbles.
Tightened it up and now no more leak.