Here are some pics, I hope they help..
In this last pic you can see how the pedals work.
The pedal itself is connected to the metal base with one bolt, check to see if it is tight.
The spring (the red part) is connected to the same metal base on the other side, check to see if it is tight there.
Now check where the two above items connect.. make sure that is tight.
Make sure your spring in the red plastic sleeve has not come loose some how.. i've never had that issue but you might.
If you have a dead pedal or one that is spiking you can see where the potentiometer is, with the three wires going to it.. I have not replaced one myself but i'm sure it's possible.
That's all thats to them.. the only thing that might make it a little difficult is if the gear mechanism that makes the pedal turn the pot is screwed up.. but i'm sure it would still be repairable.