I have a Yamaha F60, EFI. I had to pull the intake manifold off the other day to service my fuel system, and noticed the bottom chamber was a little more burned up than the other three above it. The corresponding fuel injector screen for that chamber was pretty clogged up compared to the others. Just wondering what these symptoms represent, and next steps in terms of addressing this. Is this something as simple as cleaning the screen, do I need to replace the actual injector etc.... Thanks!