I am 16 and I got my Aeropro Drive strung last July with Wilson Sensation at 58lbs. I then went to a week long camp where I played 5 hours a day, for five days. Since August, I have played 2 hours per week. Just today when I played two sets, the raquet felt amazing. My groundies were much better but my topspin second serves ended up having the same trajectory as forehand lob, which it to say, they flew much higher than normal and landed a foot long. My question is: Can this change of feel be attributed to the aging strings losing tension? And: How much tension might they have lost? I want to get my racquets strung at the appropriate lowered tension that I felt today.