I have recently purchased an old OS 120 4-stroke with the #C-13 pumped carb. It runs like a new engine, but has the common fault of loading up rich at idle, and quitting. With the idle mixture at fully leaned it still is not enough. (Yes , the top end is set as lean as I dare) {New F plugs make no difference) I'm wanting to replace the carb o-rings but can't find a parts schematic for this old engine to get the OS part numbers for the sizes. I'm pretty sure the nitro has caused the o-rings to be leaking pump pressure fuel by this time. The pump is working surprisingly well, and the throttle response is perfect. Can any of the old school glow folks help me size the correct material and sizes for these?

I'd love to get a digital page from the manual too, but seems impossible from what is in other threads.