I have a Murray riding mower that's around 10 years old, but I've taken care of it.

I had put it in the shed for the winter, but yesterday was warm so I was planning to use it for some light hauling. I checked the gas and oil, then hopped on to start it. It tried to start, but wouldn't kick. I went from choke to gas several times, but it just wouldn't start.

My first thought was that it wasn't getting gas or air. I took off the filter to the carburetor and could see that it had gas there, but I saw a little bit of cotton at the air intake. So I took the engine cover apart, and found that a mouse had built a nest inside the engine!

I pulled all of the cotton out, checked the spark plug, and checked the exhaust. I didn't find any wires chewed or any more nesting material, so I put it all back together.

But again, it wouldn't start. No change at all: it spins, it just won't start. I tried it with the air filter completely removed, too, just in case the filter wasn't letting enough air through, but that had no impact. I only bought the filter last year, so that would have surprised me, anyway.

My next thought was the safety switch under the seat. I tried starting it with the switch open (so it shouldn't start), and it spins without starting just like the problem I've been experiencing. So it's possible that the switch isn't working.

I followed the wire loom to the ignition and didn't find anything out of place; no signs of a mouse chewing on anything. There's a fuse near the switch (intentionally placed just outside of the flex loom by the manufacturer), and it has 12V on each side of the fuse, so I know it's getting power there. But when I unplugged the switch and checked for power at the plug, I didn't have power on either side. I tried it with the ignition off, on, and with someone else trying to start it, and never had power on either side.

This seems odd to me. The switch only has 2 spades, so logically, one should have power and the other not, so that the switch can make the connection. Right?

If that's right, then the problem isn't the switch, but the power wire coming to the switch. But the fuse just before the switch has power, so that would imply that there's a faulty wire somewhere along the way.

I'm asking here before I start taking flex loom apart to track down a wire, in the hopes that someone here can confirm or deny whether I'm on the right track.

For testing, would it be wrong to remove the plug from the safety switch and stick a fuse in there (bypassing the switch) to see if that works? This would just be for testing, of course; if it works then I would know the switch is bad.