Rough hook race on Singer
Now that I've gotten my Singer 403A cleaned and all put back together, I'm adjusting some settings per AndyTube's videos.
The gap between the bobbin case and its position bracket is what I'm dealing with right now. When I test it (with the bobbin removed and the top thread threaded in the needle) by turning the handwheel, the thread doesn't release from the hook when it's supposed to.
Then I put a little oil on hook race, put the bobbin case in place, and held on to it with a fingertip while I turned the handwheel. At a certain point, there's a scratchy friction between the case and the hook race.
I have tried cleaning the built-up dirt from under the hook race. What else could be causing this friction? Or causing the top thread from not releasing from the hook at the proper point?