My '76 fuji trackbike's headset has what I assume is brinneling, "index steering", or whatever. I replaced the old bearing cages w/ free bearings and fresh grease:

but that didn't help much. The headset is a tange falcon.
A new tange falcon has a race fitting of 26.4mm, and a stack height of 35.3mm. Same as my old falcon?
Could I use a tange LEVIN headset w/ 33.3mm stack height + a spacer?
Or should I remove fork and take it all to a shop and let them tell me what to get?

Here is how you figure out your stack height:

Measure (in millimeters) the steerer tube on the fork, from the fork race seat to the very top of the threads. Then measure the headtube of your frame top to bottom. Subtract those two measurements and you have your stack height.

I had a very hard time finding 1" threaded headsets at my local bike shops. I ended up buying a alloy tange passage from velo-orange and I am very very happy with it. Works great and looks nice.

As long as the other dimensions are correct you can use the Levin with a spacer.

Depending on the overall value of the bike and your available funds a cheap fix is to remove the fork race and rotate it 90 degrees.

you mean the LEVIN + a spacer? A falcon replacement should be the same, unless they have changed over the years?

Yes...I edited.

You may need a JIS dimensioned headset, which has a race fitting of 27.0. Before you buy anything, I would remove the race and measure.

could I mill down my race to fit 26.4?

DO you know for sure that you have a 27.0mm crown race?

Yes you can do it, it's best to have a fork clamp so you can rotate the fork and do a nice even job with the file. Some people will throw up their arms and say this is lunacy but I have done it more than once, these are bicycles and not rocket science so if you are careful and smooth you can do a nice job, I have cleaned up other peoples horrific jobs also with good results. However, I do have a very nice sealed specialized headset in JIS (27mm crown race if you are interested PM me).

No, I don't know the size for sure right now. I have access to a campy milling tool if I need it. I would like to replace tange w/ tange if possible but I will use other if it comes to it.

You can get Tange LEVIN CDS in either 26.4 or 27mm.

Since it's a track bike, you may want to look here for track-specific headsets:

https://stores.ebay.com/Bens-Cycle-Su...QQftidZ2QQtZkm

Why are Hattas so expensive? I could never get excited enough over a headset to be willing to pay over $200.

So I did the deed this weekend, put in a Tange LEVIN CDS, 27.0mm.
Question: the top locknut of the CDS headset has a rubber o-ring gasket just below the top. Should it be partially engaging the steer tube threads, fully engaging them, or just barely touching them? I had to use 3 (2mm) spacers to get the gasket barely/partially engaged, I would like to remove one or two of the spacers, assuming the locknut isn't bottoming out but the o-ring is fully engaged.

Mirror finished ball races. Takes a long time to get that level of finish and time is money in the machinist's world.

Does it improve performance? Probably not. I don't see how you would even notice it if you're riding on a track.

Immaterial to norskagent, but for information's sake: current Tange Falcon has cartridge bearings. Stack is about 35 mm +. I just bought one (Velo-Orange) and had it installed on a bike. It's alloy, and good-looking, IMO.

I probably should of replaced my old tange falcon w/ the the new one; I wouldn't have any spacer issues.

Here's a stock pic of the o-ring I was asking about, it looks to me like it (top of locknut) would bottom out if I removed 1 spacer...