The "footswitch" is actually just a plunger mechanism that taps on a circuit board mounted tactile switch.
Replacement hardware was available, but I can't find a link to anything right now.
Usually, replacement is not necessary. The most common issue is just that the hardware became loose. Tightening the outside nut is usually all that needs to be done. If the switches have become completely loose fallen into the pedal, the parts should still be floating around inside. Disassemble completely and find all the missing parts. There should be two springs.