First off, there's a classic tackle type shop in Sumner (right across railroad tracks off main) that sells parts. Not sure about sideplates and such. I needed some parts for my older 6001c's and some 5001c parts. He had the screws and pieces I needed and it wasn't too expensive (at least then it didn't).

Next place to have you look for sideplates is on Ebay. There's a guy who's constantly selling frames/sideplates/parts for all sorts of ABU's. I've seen old red plates for 5000A's that were like new. So check there.

That's all I got....