Improve Heineman Sound-Box using a pen:

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I noticed improved performance on my Heineman Sound-Box No.2 after replacing the original needlebar springs with the spring from a mechanical pen (a uni-ball Signo 207 pen to be exact).

The original spring on the Heineman sound-box is very stiff and has a wide-spaced coil. This coil terminates at the end without flattening out which causes only a small part of the spring's end to contact the screw head and needlebar base. This combined with the springs strong tension places uneven pressure on the needlebar and causes it to become unbalanced- putting unnecessary stress on the mica diaphragm. There is no way to adjust this like you can on a Victrola No.2, the two springs are inline with each other and only hold the needlebar in place.

-The spring from the uni-ball pen is thinner and can therefore be compressed more to achieve the same spring tension. This compression tightens the spring's coils and evens out the pressure applied to the needlebar. With this the needlebar is more aligned with the mica diaphragm and can vibrate better than with the original stiff springs.

I used the flat ends of a single pen's spring; trimmed to approximately 5mm long. Tension is adjusted by tightening the screws. It was a perfect fit and allows the needlebar to pivot easier thanks to the lighter & even pressure applied to the needlebar pivot. It was tested with a loud Victor electric recording; parts that had previously buzzed now sound fine.