Adjusting MG15 Doppeltrommel spring tension

[bbrown]

The spring tension on my MG15 Doppeltrommel needs to be adjusted for it to work with my new-to-me C&R MG15.  The tension on one side is pretty stiff, and on the other side pretty loose.  I've already cleaned out the insides pretty well (one was half full of sand).  I have a winder, board and slotted tool (representative picture below), just need to get the spring tension set.

Are there any instructions available on how to do it?  As far as I can tell, JBaum's book on the MG15 doesn't go into that.

Thanks.

Bryan