My Vermeer wood chipper has an electro-mechanical hour meter on it, and if I use the chipper for 4 or 5 hours, there is no guarantee of how many hours it will rack up on its own. One day after 4 hours of use, it jumped to 200 hours over the previous reading. This screwy hour meter worked to my advantage since it was showing about 5000 hours on the machine. It came from a rental company who told me that they noticed the same thing, and they serviced it based on the number of days it was out on rental. The true hours on the machine are under 1000, and it is about 8 years old now. I bought it 5 years ago, and it runs like a champ. There was only one time that it broke down on me, and that was when the safety bar bracket broke. My neighbor who is a machinist redesigned the part and made me 2, 1 to install and the other as a spare in case the redesigned one failed. It is so overbuilt I doubt that it will ever fail again.