Mower Deck Cleaning

I decided to pull the deck off of my x748 tonight to try out my mower axle deck stands and to clean the underside of my deck. After I had it standing upright I noticed that the previous owner didn't believe in cleaning the underside of the deck. I've mowed 2 or 3 times with it (reseeded most of my yard, plus it hasn't rained much this summer), so I'm pretty sure all the caked up grass wasn't from me. I took a 3 inch putty knife and started scraping away. In some places I got to where I could see some yellow paint, other areas had a little surface rust (at least I hope its only surface rust), and some areas no matter how much I scraped I couldn't see any paint or rust. It was just the blackish greenish color that I couldn't get through even using the corner of my putty knife.

Anyone have any suggestions on something I could use to get down to the paint on the underside of the deck so I can spray some Rustoleum and repaint. I've got a pressure washer, but I've read that you shouldn't use them on decks due to water getting in the spindles or bearings. Any suggestions would be appreciated.

Thanks
J