I was using my tractor yesterday and suddenly my control pedals would only engage a small amount. The tractor would move, but only at a very slow speed. I immediately thought I had jammed something into the linkage. It took me a few minutes to figure out that the problem was with the brake linkage. The arm (#29 in the drawing) had slipped off of the pivot pin. Clearly I lost the retaining clip #27 and spacer #28 (which looks in the drawing to be more or less a washer. I can't fathom what would cause this to fall off. I slid the arm back on the pin and finished the job. It did not come off again. I thought this was very odd.
The parts appear to be very cheap, but not available at my local dealer. Clearly I want to fix this, but am wondering if I should just find an off the shelf retaining clip and washer. Any thoughts on the original issue or how critical it is to replace with the OEM part?