Hi John:

I have a 190 that probably needs alignment one of these days. I would
certainly check the paper caps. Years ago I had an old HT-32 that would not
null anymore. I replaced every component in the circuit, yet it was still
unbalanced. I finally put in an completely different circuit - which worked
great on ssb but gave up am.

Decades later, it suddenly dawned upon me while working on a different
circuit that there was a leaky paper cap just outside of the circuit that
caused all of my grief.

Sorry about the kHz / cycles bad joke - but you started it.

Good luck, Colin K7FM