I don't have A-stars, but I've read the prev. posts fairly thuroughly. The replaceable part on the A-stars is the small insert under the arch of your foot. That part can be removed w/a utility knife and heat gun and replaced w/some glue(and maybe something else like staples, but that's the one part I can't remember). To replace the whole sole is a whole other project. You have to take the boots and new sole to a shoe/boot repair shop, due to the stitching required. If I remember correctly, you can get some new soles for around $20. From what I've read, you can also use different soles on your boots. I saw that, seeing as the tech 8's sole wears so quickly, others have been having good luck w/the Gearne's SG-1 soles.