I was gonna try to clean my power valves today for the first time since I've owned the sled. I pulled the black and red covers off, caught the spring, and that was it. I got to the round green/tan thingy wrapped with the spring and it was free and moved fairly easy, but wouldn't come out. I took out the two socket head srews but nothing came out. Does the valve pull out so I can get the crud out of there? It felt like it didn't wanna come out. It's new to me to have this set up so any pointers would be great. Also, is it better to use synthetic oil, if so, which brand?