I'd switch to .018 Pillow ticking. After using it one time, i'll use them forever! As for the ball being centered on the patch, All you can do is give it your best. I dont think it will make a difference if one side has more sticking out than the other. Unless its an ungodly amount.

Did you find any recovered patches? It could also be the lube thats on them. I know factory bore buttered patches i used to get did not come with enough lube and they'd burn right up.