I NEVER borrow anything...that has become one of my hardfast rules. I learned this the hard way, whenever I borrowed something it broke, no matter how careful I was.
A few years ago my father-in-law was on me to use his ridding mower to suck-up and bag the leaves in my yard instead of raking. I told him that I would rather rake, but he insisted and my wife suggested that I use the mower, so I gave in. My father-in-law instructed me to take the bag off and chop the leaves up, then put the bag back on to pick up the leaves on the second pass.
All was going well as I chopped the leaves up until I notice a burning smell.... I looked back at the engine and leaves had blown up onto the exhaust and had caught fire!
I quickly stopped the mower, and as I swung my leg around to get off, my boot hit and snapped off the key in the ignition
I could not shut the engine (that was filled with burning leaves) down... I ripped my sweatshirt off and beat the fire out, then when it was safe I pulled the spark plug wire.
Thankfully the damage was not too bad and we were able to save the mower.
This is one of the reasons that I do not borrow stuff.
Chris