So after 35 years I have removed the Shimano freewheel from my original Puch racer, stripped and cleaned it and put it back together withoit losing any bearings. Phew. It was very gunged up. But the two internal shims have been damaged and whilst I tried to realign them, the outer bearings bind when the lock ring is tight. If I loosen it a bit then the freewheel works great again. I cannot find a source (or size) for those shims - can anyone point me in the right direction. I have ordered an EBay freewheel replacement but really want to get the original working. Thanks in advance.
I don't know of a source which sells these parts new, but...
As a volunteer at the local bicycle co-op we literally have a bins full of old freewheels and sell them for a few $$$. If you have a bicycle non-profit near you, I would be surprised if you cannot find a couple similar freewheels which you could use for donor parts.
There are Facebook groups which cater to vintage bicycles and many folks in those groups either sell vintage parts or know others who might have a source. Here are a couple:
You could also check with some of the online groups. The Velocipede Salon has A LOT of members who are (were?) long time bike builders, mechanics and shop owners.
Good luck with your search and feel free to contact me directly and I can see if the Co-Op has a similar freewheel.