Does one measure belt deflection on the longer run to set correct belt tension? If so, what is the figure sought? Or does one increase tension just until no belt slip occurs under no-load condition?
I don't think anyone actually measures the tension, so long as it doesn't slip when you're motoring along thats all that matters :)
If the belt is worn out or wrongly set up you will know by the loud buzzing noise when you engage the motor.