Gday Matt and Nath,
Nath is on the money with suggesting careful lubrication of the square drive. That said I�ve had a recent experience where the problem was the pedal pivot. The pedal was binding and causing odd binding behaviour that had me suspecting a drive problem. I ended up having to get quite energetic to get the pedal off the post. Cleaned it up and put some anti-seize on it and all was good again.
The point I'm trying to make is to check the entire drive system from the pedal back for freedom of movement and lubrication.
As Nath says I'd be surprised if there is broken springs or the like.
Let us know how you get on.
Cheers,
