What are the maintenance intervals for? Why intervals 1 and 2? It says the lone wrench only appears once, at 100 hours. When does the wrench 2 appear? At 100 hours also? It says consider mileage and operating hours to determine appropriate interval to follow on the maintenance schedule. There's only one, 100, 600, 1200, etc. miles, or 100,200,300, hours. Which other one could I follow? I don't get it.