SteveH

Ok, let's start with the term "Vibrate" It is defined as "to move back and forth or from side to side with very short, quick movements" (Merriam Webster)

So, the action of the shuttle carrier Is the "vibrate" that is referred to. This was done originally to differentiate these new machines and their design from the older "Transverse" (Movement side to side) sewing machines.

There is no adjustment of the shuttle carrier movement. the adjustments are tension and stitch length, that's it.

I am sure someone will chime in with a link to the manual soon, if not I will at my next break