I also had my DFP for 18 months before the pedals started spiking. I emailed customer support with the problem and after confirming when and where I bought it (they took my word for this, I didn't have to send any proof of purchase) they sent me new pedals AND a new wheel within a few days.
I believe the guarentee is 2 years, in the UK at least, so hopefully you'll get the same result as me.