I have knitted socks with a kit that I got from the Red Cross as a collectors item from WW2. It contained a pattern, yarn and needles for the period. The pattern was knitted from top down and easy instructions for turning a heal. The sock pattern made tall top socks for combat boots. The yarn was army green. The pattern did not have any instructions for replacing the heel. I did get some of the new yarns out there with nylon contained in it. It was yarn for making socks. I know I made several pairs and it was pricey. Good luck, I think I would darn the heel

I am a huge sock knitter, knitting one as I type, yes almost at the same time. I know there are double heel patterns that one knits in while maming the sock, not replacing it once it's gone. I have to learn this as my sister's keep falling apart at the heel. I am a toe up pattern lover, but taking advanced lessons in toe down to learn new strategies. I've knit forever but one can always learn new things. P.S. There is a youtube video on reinforcing socks and toes. I just looked it up.

More info. GO to 3sleeves.blogspot.com. She shows a beautiful double heel and she has a pattern on ravelry.com. My favorite pattern place

I am also a sock knitter. I knit a lot in the car since we are at least 1 1/2 hours to the nearest city of any size. I use the magic loop method and am a top down sock knitter. I have a book to learn toe up and will have to work on learning that method. I had not heard of replacing the heel. I am going to Utube and check out reinforcing the heels and toes. So far I have just mended them. Love to learn new things.

Some interesting articles on this! http://www.tinkingturtle.com/2014/01...to-repair.html