How do you adjust the belt on these change the speed? Not the positioning on the spindles but the actual moving of the belt? Is there a special tool for this, do you loosen a spindle? Do you just force it with strength? I'm one of those underprivileged Catholic school kids who never grew taking shop and come from a family of white collar parents. I'll have tons more of embarrassing questions to ask as I get more into the building side of things.