Surprised no one has posted on this topic yet; here goes:

My Kenwood TM-221 has a problem with the intensity of its PL tone
output level. Mine is too loud, generating frequent reports of "hum"
from others.

I have the original manual with schematic and block diagrams, but no
obvious information indicates where the output tone is generated or
adjusted.

Not being wizardly and knowing there are wizards hanging around here,
I'd like to know what pot needs adjustment to settle it down to the
right level, if one exists. Anyone?

Bonus question: I have the same problem with an Alinco DR-590; if you
can help me with that too, that would be nice.

TIA, KA1IOR