You’re saying the installed height changed about .100.
That’s about 5 times what the valve lash is....... so, we know it can’t be the valve tip height being raised that much, since the lash didn’t go to zero a bunch of times.

This leaves either a parts failure of some sort(keeper pull through, etc), or assembly/measurement errors when the heads were put together initially.

I would think if the retainers have moved up .100 on the valve stems, there would be evidence of retainer to rocker interference........since there is often less than .100” to spare.
It’s also unlikely(though not impossible) they would have all failed the same amount........ so you could look for a lack of uniformity in the relationship between the top of the valve and the top of the retainer.
If the retainer/lock/valve interfit was compromised enough to change the installed height even .010”, I wouldn’t reuse any of it.

As I said....... time to pull the heads, inspect everything, and start over on the spring set up.



Can you explain that a bit more? I’m trying to picture why you’d have to wrestle with the locks when there is no spring tension.