I am running braid right now (125 yards or so) Should I fill the back end of the spool with mono and tie to that?
Hi. As Alan indicated above, most times, a direct connection of braid to spool, will result in the entire whack of line spinning around the arbor, mimicing no drag. To test, lock the spool by placing your thumb on the sidewall, and pull out the line, if all the line slips around the spool arbor, then the connection needs adjustment. Old school was to wind on about 15 feet of mono, (as per Bryan's post) and tie the braid to that, but that takes time, and the unique mono-to-braid knots.
Current thinking is to tie braid to spool, then overlap with a layer of adhesive tape. Or: place tape on arbor, and tie line. Either way, the braid bites the tape, and won't slip.
On your original post: IAR = instant anti-reverse. If the braid is secure, and you still have no drag, then the washers are contaminated with tramp oil/grease.