My wristwatch is regulated by one spring, so is my Hayden.

 

Have you noticed a difference with only one spring?

 

The reference:
My OEM Regina® tensioner had not failed, so I was able to compare the initial spring force (needed to collapse the shoe) to industrial specifications for chains of identical size/mass. Regina® makes chains and tensioners for machinery so they carry, publish and can gave you information.

The "upgrade":
-I had to deburr and polish the steel cage of the Hayden® to limit unnecessary wear of the shoe.
-I slightly modified the well inside the shoe to ensure it's base could rest flat inside the cage once compressed (when starting the engine and down-shifting harshly). The small spring I received was 1mm too long and could have deteriorated the shoe.
-I measured spring forces obtainable by combining both springs. The large spring gave me the specified 25 pounds I needed.

Since I installed my reworked tensioner I simply forgot I had one