Have been finding Reels with 2 Head Shims latley.
I normally add one if their is lateral movement in head.
One Reel (1963) was like new inside and had two, but still had excessive movement in head.
I added one more which took care of the problem.
A while back was told not to add shims.
Me being a retired Aircraft Mech. Did not take that advice.
The fact is if you add a shim and problem gets worse, take it out.
Watched several reels I added shims used them took apart and did not find any wear or problems.
Always keep notes on how a reel was shines up when you clean and service add shims if nessesary.