[HBR] Need advice on Miller 1730 transformers

[Werner, HB9BNK]

Back around 1970, I built a HBR-13C (with great help from Alex 
Stewart). Having studied the valuable reflections-CD and the 
discussions here, I recently pulled the receiver from the attic 
and try now, to get it running again - and improve, if possible.

Now, I found, that some of the I.F.filters cannot be tuned, 
because the core's are locked by whatever ...

Can someone give me an advice, how to free the core ?

Thanks and 73

Werner, HB9BNK