Hey guys, wonder if you can help. I'm a 17 year old from the UK starting on the ITF Futures tour this year. I'm 6 foot 5 and really should have a killer first serve, but it's only really up to about 110mph if I'm lucky! I know I should be winning a lot more service games than I am doing and I just can't get to the bottom of the problem! I have a problem with the joint in my shoulder and it moves out of positions if I hit big when I'm not warm... Any ideas on what I should do? Cheers!