The side panels are held on with a 5/16 truss head screw that uses a flat head screw driver. Korves Oliver has a kit that has all the sheet metal bolts you should need, and they are all stainless steel, so no need to worry about rust that way. A bolt supplier should be able to get them as well. Korves might have the oil filter base, as they sell reconditioned engine blocks, and I would think they would have an extra one around off one of those blocks. If Korves doesn't have the filter base, I'd be willing to bet the Maibach's would. You can reach them at 800-808-9934.

Your plow sounds like it has the hitch in the wrong spot, or the plow is just not running level. The plow frame should be level left to right and front to back when it is at operating depth. It may seem backwards, but you may have to shallow up the furrow wheel to get the rear to plow deeper.