The Jargon File (version 4.4.7, 29 Dec 2003):

frobnicate
 /frob'ni?kayt/, vt.

    [Poss. derived from frobnitz, and usually abbreviated to frob, but
    frobnicate is recognized as the official full form.:] To manipulate or
    adjust, to tweak. One frequently frobs bits or other 2-state devices. Thus:
    ?Please frob the light switch? (that is, flip it), but also ?Stop frobbing
    that clasp; you'll break it?. One also sees the construction to frob a frob
    . See tweak and twiddle.

    Usage: frob, twiddle, and tweak sometimes connote points along a continuum.
    ?Frob? connotes aimless manipulation; twiddle connotes gross manipulation,
    often a coarse search for a proper setting; tweak connotes fine-tuning. If
    someone is turning a knob on an oscilloscope, then if he's carefully
    adjusting it, he is probably tweaking it; if he is just turning it but
    looking at the screen, he is probably twiddling it; but if he's just doing
    it because turning a knob is fun, he's frobbing it. The variant
    frobnosticate has been recently reported.


The Free On-line Dictionary of Computing (30 December 2018):

frobnicate

   /frob'ni-kayt/ (Possibly from frobnitz, and usually
   abbreviated to frob, but "frobnicate" is recognised as the
   official full form).  To manipulate or adjust, to tweak.
   One frequently frobs bits or other 2-state devices.  Thus:
   "Please frob the light switch" (that is, flip it), but also
   "Stop frobbing that clasp; you'll break it".  One also sees
   the construction "to frob a frob".

   Usage: frob, twiddle, and tweak sometimes connote points
   along a continuum.  "Frob" connotes aimless manipulation;
   "twiddle" connotes gross manipulation, often a coarse search
   for a proper setting; "tweak" connotes fine-tuning.  If
   someone is turning a knob on an oscilloscope, then if he's
   carefully adjusting it, he is probably tweaking it; if he is
   just turning it but looking at the screen, he is probably
   twiddling it; but if he's just doing it because turning a knob
   is fun, he's frobbing it.  The variant "frobnosticate" has
   also been reported.

   (1994-12-16)