This is an easy fix! The second-gear cone and second-gear brass are not compatible.
It would have been better to do the diagnostic with the trans still installed,but...
Since it's out, you will need to tear it all down again, and clean all the oil off. Remove the second gear brass and mark it.Do not mix it up with the rest.Check the flat large face. If it has made contact with the gear it will have an odd-locking swirl pattern. Also check to see if it is cracked.Either of those make it junk.
Then take the input gear in one hand and fit each one of the other three brass onto it. Give each one a little twist clockwise with very light pressure. It should immediately lock onto the polished steel cone. And after it has locked on, the higher up away from the base of the cone, the less worn the brass is.Arrange them on the table in a vertical column, from fastest locking on the top to slowest on the bottom.If they are all about the same fast-locking, then arrange them from the higest sitting to the lowest on the bottom.
Take the top ring, the fastest locking or highest sitting, and put it onto second gear, and retest it. The second gear brass is the hardest working one so it has to be the best it can be.So give it a twist with very light pressure as you did on the input gear. Does it still work the same. If yes, then set that gear aside together with it's new mate.
The next hardest worker is the downshift side of low gear, so grab it in your left hand, and grab the next best ring from the top of the column, and try it, also twisting it clockwise, with very light pressure. If it locks nicely, set that gear aside with its new mate.
And then grab third gear, still in your left hand, and the lowest ring from the column, and try it. But this time twist it counter clockwise, with very light pressure. If it locks nicely, make it a set.
That just leaves the input, the least worked gear of the bunch. So go get that marked brass. Now you have practiced long enough and know how things are supposed to work. Give it a try,twisting clockwise. My guess is this one will not lock properly. But if it does then they are a set. But if it does not, it's probably pinched oval. Set it on the cone very lightly and check it for a rocking action. You may have to try it in many directions, removing it each time for a new test. If you find it does rock, then it is oval, probably from being dropped.
At this point you have two choices; 1) buy a new one, or 2) straighten it.
I have had very good success straightening many many of those.
So if you pick #2, then you have to figure out exactly where the pinch is, and unpinch it,lol. So find it and mark it with a sharpie. Then rotate it exactly 90* and stick it in a vise. Bring the jaws into a light contact, and pinch it a tiny bit, then refit it. If it still rocks, repeat the pinch, on the correct axis, a little bit tighter, each time until the ring locks on. That is the proof of success;when it locks just like the others did.
Finally compare the locked-on heights and make sure they are all about the same. I have no spec for the minimum height. But I could hazzard a guess that the lowest should be better than 80% of the highest. So if the highest is at .080 then the minimum would be .064. Not very scientific I know, but it's all I got
Now, if any ring fails to lock onto a particular cone,you will have to prove if the problem is in the brass or on the cone.The easy test is to try another brass. If another brass works then the very first brass is either oval, worn out, or no good.
Mix and match until they all lock.
But in the event that one particular cone will not accept any brass, then that cone will have to be polished. And if I do one, I do them all.
And what I do is put each one on a lathe, square it up, and turn the lathe on at about 600rpm or so, and the top spinning away from you. Then I take a strip of emery cloth of about 120ish grit stretched end to end on a lathe-file, and give her a stroke or two with a moderate pressure, against the rotation. The emery goes onto the cone from bottom to top and I put a bit of extra pressure on the base of the cone, as it is spinning. Two strokes, stop the machine, clean the cone, and fit the brass.Repeat if necessary. If it locks on very easy and hard to get off, then follow up with a finer grit,say 180.And retest. It shouldn't takr more than 4 to 6 strokes, but that could vary until you get the hang of it. Leave second for last, after you have had some practice. Low gear may not fit on the lathe; I had to manufacture a stump/clamp. But low gear is the least problematic.And if you get to work too well, then sometimes that is not a good thing; making engagement atta stop difficult as the clutch teeth may get caught butted up.
Ok so have at it, and good luck! Soon you will be a Pro and doing everybody's trannys for miles around.
Now you may be tempted to just buy a new set. And that's not a bad idea. But you still have to go thru this entire procedure to be certain that the new rings are not oval, and that the cones are gonna grab them.
