Had my bx2680 in to the dealer for another issue, they had to take of the fuel tank. I wanted them to change the fuel filters while they had it apart. I was informed that a fungus was in the bottom of the tank. They asked if I use biodiesel, I don't but maybe it has a mixture of it in the fuel. Anyway this could be part of your problem.
Is your battery good? Connections clean? If the cranking speed is a little slow it will be hard to start. Check the basics first before you take anything apart.
