Threaded Headset / Problems with 1" Headsets

The top threaded race has reached the end of the thread on the forks so adding spacers would not cause that part to sit any lower.

Edit: apologies, just read your post correctly. You need to tap a longer thread on the forks. AFAIK there's no way to add spacers below the headtube and fork crown race always sits tight down on the fork.