fc60
It's a Star Machine & a Star Head.......
I tried another Star head and it works perfectly....

All the heads I've seen Don't have that oil groove.....

I took the KEY out of the Head thinking it was the problem

It wasn't.

I understand about the Spiral cut, But, it still could need honing/lapping...

The head slides down approx 2" above the Base, it sounds like it's hitting a ledge

I'm not sure I understand about lapping or where to get one

Funds are tight, so self repairing will have to suffice...

Just tried another STAR Head>>>WON'T GO DOWN ALL THE WAY...
I miked the Column Shaft, it varies from:
TOP:: 1.188
1.191
1.196 Middle
1.194 At the base of the Key-way