Shaker motors are a relatively newer additional to pinball machines.  It's a great haptic device that lends itself to more immersion into many table themes.  However, the stock configuration of the shaker motor can be pretty intense and lend itself to shaking components loose, creating a great deal of rattle noise in the glass without tape, or feeling like the table is going to walk itself across the floor.

There are software adjustments that will adjust the frequency or the duration the table will use the shaker, but nothing for the actual intensity of the motor shake.  The good news is adjusting the position of the motor arms will change the overall shake intensity.  

High Intensity

This is the default configuration, as shown here:

Full strength weight arm alignment

Both of the weight "arms" point in the same upwards direction in the image, which cause more vibration from the weights working together at full strength as the motor spins.

Medium Intensity

Loosening and removing one of the set screws for a weight arm with a hex wrench allows turning one of the arms to 90 degrees off from the other arm, as shown here:

Partial shaker motor weight arm offset

In the picture, one arm is pointing down, the other toward the camera.  This configuration will drop some of the shake intensity.

Low Intensity

Removing both weight arms allows setting the weights completely offset as shown here:

Fully offset shaker motor weight arms

The image shows one arm pointing away from the camera and the other pointing toward the camera.  This configuration is my preference since it still allows players to experience the haptic feedback shaking without being as intense.