This is what John @ Sipsy River told me and it has worked every time so far:
Do the field point as described above, being careful to keep heat only on the point. Count about twenty seconds with a propane torch. Place point in a vise that was previously set close to the size of the point so it is quickly placed in the vise and tightened. Be set up so at this point you can pull straight back on the shaft. If it comes fine if not reheat about five to ten seconds more and repeat the vise/pull. Also have a bowl or can of cold water nearby to plunge the shaft into as soon as it comes loose. I've done it a lot and it has worked fine every time for me. Again be careful to only apply heat so that it doesn't hit any of the shaft. I found it takes a few seconds for the heat to soften the glue. It will come off with a little bit of force. I also found when tuning it does not take but a little bit of glue to hold the inserts in and they are easier to remove until you get them like you want. The ones though that I was working with as john first told me, were ones that he had glued the points on so they were tight! His advice, as usual, was dead on. Hope this helps!