Reverb Rebuild and Adjustment 1484

[scstill]

Continuing saga of the Silvertone 1484...

Before going the route of a new reverb, I decided to open up the original unit. Refurb included new paper insulators at the 4 spring contacts (originals were quite brittle) and a new thread guy line for middle support (orig was broken). On test (see pic) it sounds pretty good so I will stay with it for now.

My question is on adjustment.
I can tighten or loosen the spring by moving more or less coils to the non vibrating area at each end between the contacts. I cannot really tell much difference in the result, although it "seems to be better" when the spring is set naturally without tension. Should there be a difference? 
What would be an "ideal" spring tension adjustment?
Any theory to coil air spacing or spring tension?

[sluckey]

Even the Sears engineers didn't put that much thought into it. Just play it like you stole it!   

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Even the Sears engineers didn't put that much thought into it. Just play it like you stole it!   

Part of my journey is to learn from people who know more than me. That was the reason why I came to this forum.
Certainly there is more to spring reverb theory & design than an arbitrary spring connected to the circuit.
But since there is not a discernable sound difference I will button it up and play it.