Ummm, dumb question - but have you stuck it in the dishwasher on it's hottest cycle?

Try that before you do anything too radical.

Gives the same effect as flame polishing. (and you don't set fire to it!)

P.S. try and support it as much as you can - it could theoretically warp under it's own weight. (I did the Party Zone main ramp unsupported without any hassles)

I use 70deg 2hr20min cycle. Put the ramp in the bottom rack (It's hotter).