Put your finger through the hole and see if the race is down to the step in the casing
I've tried that but my fingers are too big - I've tried bending some thin feeler gauge into where my fingernail should be but can't find a gap / ridge so it must be okay I guess - a few bumps in the road might help then it can be adjusted fully (I dont want to risk overtightening it) - I have screwed the slotted head top adjuster down by hand - it's screwed down okay with the threads just about to peek through the top of the threaded nut if that makes sense.
I have used a taper roller with a 3 mm spacer in the bottom with standard plain ball bearing at the top. Just found that my top domed nut thread is a bit flattened looking so I aim to try to get a replacement if available if not I'll have get a tap put down it. The column thread looks good.
Just looked at the shape of the frame column and compared the depth at the top enlargement with the old bearing race it must be seated okay - I've been thrown off course a bit by the bottom that has a much deeper recess. I'm a happy bunny now.
