Oh what a worn out the striped socks have faced during the years. I could have just darn it but the damages were quite huge at whole soles. The leg parts were still quite ok so I decided to knit new feet parts for them. I just cut off the feet and heel parts and picked up the stitches on needles.
Then I knit new heels and feet parts. White and grey are the same shade as the original ones. The blue is new but matches well. I used Novita's 7 Veljestä (75 % wool, 25% polyamide) (100g = 200m) yarn. The original pair is made of Novita's Tuomas yarn (100g = 189m) (40% wool, 35% acrylic and 25% polyamide).
By knitting just the new feet for the socks I saved my own time and the nature resources!