Ronzara,
...your blocks are too small (sanding...not engine!) Niles has it right. You need a long-contour sanding block that FLEX's.
You might have noticed that the cobra body has no flat areas, unless you sand too long in one spot.
Be prepared for about 5 weeks of work, and look for the "waves" by setting up lights downstream. It's a hassle but better you find them now than after spraying.
PS... I cuss in church stronger & faster than you...
scratch
