My sister has an old Aerotus 110 racket and has recently started to play a little badminton. This racket is about 11 years old, is it still ok to string it? She's going to be playing very casual, maybe once every 2 weeks. She's not a smasher, she likes to drop and drive a lot. She hasn't played for about 10 years, so her technique is very rusty, her swings are not fast. Playing mix doubles most of the time. What string and tension would you suggest? Thanks in advance!