Stupid question but how do you measure belt deflection? My belt is about flush with the top of the secondary.
Place a Straight edge (approx 18" long) across the top of the belt from above the primary to above the secondary
Push down on the middle of the belt
Look for 1" to 1" -1/4" measured down from the straight edge
As a GENERAL rule, run the belt as TIGHT as possible (secondary as close as possible, resulting in belt as HIGH as possible resulting in better acceleration) until the sled "creeps" forward at idle, then loosen it up a little from there by "opening up" the secondary