Is it really necessary to lock the cams? Surely if they move when you take the old belt off, it's just a case of lining the timing marks up again and making sure there are the right no. of teeth between each mark?
Yes, but some of them will be under tension so they don't want to stay in the same place when you let go!
I'd rather die peacefully in my sleep like my Grandfather, than screaming in terror like his passengers.- Jim Harkins