I was tinkering with my '96 cocker that also doesn't have a timing hole and found a new trick to time it without removing the grip frame everytime...
Take the grip plates off the grip frame then the spring that pushes the sear up. After that, slide out the sear pin and shake the cocker nose-down until the sear falls forward. You should be able to see and adjust the hammer lug after that. Put the sear back in place plus spring and there you go. MUCH more painless than taking off the grip frame and more precise than fingering it.
Hope this helps,