I'm having the same mysterious drivetrain problem. My pedals are less than two months old and were brand new when purchased, but the sound I'm getting is the clicking at several points in pedal rotation while I'm pushing hard. It's gotten more pronounced over time and especially when I retension the chain after it gets a little loose. I don't think it's the crank arms and the bottom bracket is sealed, so it's probably not that. What should I be looking for if I disassmble the pedals? Would MKS Sylvans be made so poorly that they sound like death after riding them for two months?