Quoted from Sinestro:
The shaker setting doesn't control the power of the shaker....just how often it's used.
Sinestro is correct that setting may control how long it spins , definitely how often it spins but the force can only be changed with a mechanical calibration.
To reduce the force from your Stern Shaker... Loosen the set-screw on one of the weights.
From the factory, the weights are set the same.
Now move the loosened weight to 90 degrees out of sync with locked down weight.
This makes a huge difference. I would not even use my shaker until I adjusted it reducing the shaker effect.
Note: If you were to set the weights 180 degrees out of phase the shaker would not make any impact so set accordingly.
Setting at 90 degrees cuts the effect to 50% of factory setting , which I feel is perfect while others love the earth shaking impact of 100%.
** Loosening the set-screw is not easy.
The screw is glued in on the Stern Shaker, but you can do it.
I used my surface mount hot-air tool with a fine nozzle to heat the screw and the glue which made it easier, while others have just used brute force.
* Use a right angle hex key (not the Swiss army knife style) .
* If needed you can lock a vice grip on the hex to add length which in turn adds torque.
* A thick rigid pipe of the right size slipped over the hex-key handle will also work to add torque.
* Only use a key that fits perfectly in the screw. The perfect size is 3/32" .
* Cheap tools can have poor size tolerance .