Hi,

Try calculating the number of partials based on the highest frequency
expected by the sound source.  Don't use anymore partials than this for the
lifetime of the sound.  This may work if the vibrato is within a narrow
range.

For portamento try adding a declick envelope as each new harmonic is
introduced or removed.

kdclick linseg 0, .002, 1, p3-.004, 1, .002, 0

Even though the manual states that there may be audible clicks when sweeping
frequency with buzz I haven't really noticed them.

Regards,
Hans Mikelson