When you first setup your trampoline frame, here is a little tip.
Pop all your springs in their holes in readiness for putting your trampoline mat on.
Now as you will see here in the photo the circular parts of the frame are not quite butting together properly.
A lot of people wont notice this and simply proceed to put their trampoline together.
Now the tip is before putting your mat on go around to each join in the circular part of the frame and undo these joining screws slightly so they are not tight.
What happens now is as you put your mat on and start joining all the springs to the mat it starts to put pressure on the frame, and with these screws being loose slowly but surely the frame pieces butt in together a lot better.
It gives a firmer join and keeps your trampoline slightly more stable. If they are not sitting quite flush a small tap with a rubber mallet or hammer will make sure they are seated properly.
IMPORTANT NOTE: Remember now to go back around and tighten up all the joining screws.