Hi Patrick and welcome here! I'm shortsighted with 1.75 diopter on right eye and I see a clear difference while rotating the ring. If the diopter adjustment ring is rotated fully left, it makes the VF blurry to my eye. If I turn the ring completely right, the image is sharp as it should be. There is just a little too long way between boundary positions and there may not be visible difference if you do not rotate the ring long enough. In any case, if you see clear and sharp image, there is no need to worry about diopter adjustment ring
The funny thing is that I don't hear or experience any "clicks" with my VF-1? The ring just rotates around its axis with no sign of "clicks" (unless I'm totally deaf or click insensitive). How many times you can fully rotate the diopter ring around its axis?
On my VF-1, the little mark on diopter adjustment ring points to 6 o'clock. And I can fully rotate (360 degree) the ring 4 and 1/2 times (no clicks at all) and I see clear difference when the ring is rotated fully left and fully right. I can probably rotate it a bit more (with force), but I'm afraid to break the plastic screw. Maybe the broken thread is why you hear the "clicks"?