I got a 1970 Power Mac 6 runs great but when I bought it it was missing the spark arrestor screen. I took a screen that was large from an old craftsmen that I use for parts. I cut it to fit the shape of the Mac muffler. However, I wen to cut today and sparks were coming out. I did notice that sparks were coming when the saw was at full rpm with no load on it. When it had a load in the wood I looked multiple times and did not see a spark. Is my cut job not good enough I did my best to make it fit the size of the muffler. Will the screen need cleaned already. Also, is it possible that I may need to tune the high setting on the carb? Thanks all.