I have had similar with the brake switch , on a John Deere riding tractor . But will tell you , don't replace automatically the brake contact switch . First locate it (as you have the schematic) and try this , as most times it is Moisture/oxidation , that is preventing a good contact(and do same with seat contact) . Since they are simple electric contacts , back to the circuit board . So carefully use a brass small wire brush , or even 500 or even 1000 grit sandpaper .....Have even used a razor blade on occasion , to clean off any oxidation . IF , the oxidation , is on the circuit board , where the solder is not making good contact , use some rubbing alcohol , to clean it with a cloth , be very careful , and make sure power is NOT on the board . Maybe even using some solder cleaning flux , if alcohol does not work . Can use a power meter , on board , to make sure of any power interruptions , with the circuits . IF you have never tried or done that before , brush up with a you tube video . Will save you literally hundreds , to NOT have to rely on a mower repair shop , that will just replace ALL the associated parts , (MOST TIMES) and then charge you the spensive labor to replace those spensive parts .......So a few minutes work , will keep you from dragging riding mower to dealer .......Best of Luck , Happy 2023.......