Clunking Sound Switching Octaves While Running Sequencer

[New2Synths]

Hello All,
I am new(er) to synths and have a question I cant seem to find an answer to when I google it...
On a Moog Grandmother or Moog Subsequent 37 when I am running a sequenced pattern and flip from one octave to the next up or down getting a "clunk" sound is not unusual.
By clunk I mean its not clean and is audible (boomp, clunk, etc.).
Moreover, two measures of one octave then when I switch to another octave its not seamless (I switch during the space between notes not in the middle of a note).
I really like to, for example, occasionally go: 4 notes-switch-4notes-switch-etc.
Maybe its the nature of the beast-I try to time it perfectly which seems to help but if I am off a little there is the unwanted noise.
Rests in the pattern are a good place to switch but even something at 100bpm its not easy to be flawless every time (I am a drummer so the timing isnt necessarily the issue).
That being said:
On a Moog Little Phatty pushing the Octave Buttons work fantastically-no "clunks" so I question the G.M. and the 37.
Any questions if I am not clear and any comments will be greatly appreciated.
Thank you.