@Bldtrailer:
1.) The Polyrope needs to fit tight. If it does not this method will deliver bad results.
I would recommend 1/4" braided polypropylen rope from Menards/Lowes . It fits my Goldtips tight, but still comparably easy to install.
2. By completely filling the arrow you add more mass to the rear of the arrow, which stiffens it and may have changed your spine. The added mass all over the shaft "weakens" the dynamic spine very slightly. If your setup was on the weak side of the spectrum, it may be now too weak. Try only filling it 2/3 in the front and refer to 3!!
3.)If you only partly fill the shaft, then you need to glue the rope to the back of your insert, so it can not move inside your shaft.
Remove your insert, pull piece of rope from nock end through with serving thread up to about as far as the insert will get in. Thread serving thread through hole in back of insert. Put epoxy on back end of insert and on sides and press insert in.Pulll on serving thread to make sure rope has contact with back of insert. Let set with nock end pointing down, to prevent liquid epoxy flowing throught he hole into the threaded part. After epoxy has set, cut thread with razorblade as deep in the insert as possible and thread fieldpoint in. The threads will destroy the rest of the serving material with no problem. Like that, you can balance your arrows like you want and to almost every weight desired, depending on rope weight and length.
If done correct, rope filling has almost zero effect on spine. I shoot a korean bow, that I shoot over the knuckle and which is cut like a selfbow. Weight tubes do not work there,but the rope does. My arrow must be very heavy but comparably weak in spine, because it has to flex more around the grip. I use the rope method also with my demonstration arrows for the bows I sell. I have for the same bow arrows in different length and the same gpp ratio from 28-32". This will give the customer the right impression about his hunting arrow speed.