RE: How to tell draw weight without a machine?
If you are trying to get the weight down to accomodate the spine of your new arrows then I would just do a re-tune (you probably should anyway) of the bow. Setup up centershot, turn down the limbs and start tuning. Then, instead of adjusting your rest left or right just adjust the poundage up or down until your arrows are flying correctly. Then everything will be setup to work together.