Know this is old news - but I haven't been able to decide where my noise is coming from so I can fix it.

1969 2J 11/2 HP varispeed

I have experimented based on previous posts and have found out this so far.

Mostly quiet in neutral
Noisy in high sounds like knocking or a chipped tooth while running
Slight noise in low same sound as high
Spindle TIR around .0005
Spindle has spline slop in both high and low
I had the head rebuilt supposedly less than 100 hours ago. It was done off the machine - new belts etc. It was noisy when I put the head back on think I got shafted but have since moved me and the 2J across the country so ----------

Looking for help in being able to identify the problem before I buy any parts for a fix. What do I look for and where?

Thanks in advance