First forget the rollers, go to the rear poulies, where your pressure feather, go stronger in the feather and stop when the v-belt is tight between the poulies, then your pressure feather is good, the v-belt schould be standing tight between front and rear poulies. then concentrate on the weight of the rollers, start with something like 4 grams, and then if you thinks it makes to much rpm go to 4.5 ore if waye to much go to 5.5. and so on...