Just in the past week, I have serviced two snow blowers with this problem. The first was a practically new machine that had been in storage for the off-season and wouldn't start. Upon closer inspection, mice had made a home in the gear box and chewed up the ignition wiring, rendering the almost new snow blower useless. To the left is a picture of the machine with the belt cover off. Fortunately, the mice had not eaten the wiring in the other machine. But the point is, rodents can cause tremendous damage and costly repairs to your equipment. Here's another example of that: Snow blower vs. mouse.
To prevent this damage, I recommend keeping a couple of active mouse traps in the shed or garage nearby your equipment. Hopefully, the cheese will look more appealing that your equipment wiring and you will be spared the headache and expense of mice destroyed outdoor power equipment.
Feel free to post your Mice vs. Machine comments, experiences, or suggestions below.