Worked fine except for the 400 and 1000 cps tone and the external modulation weren't working. Advice was to get rid of the old mica-molds in the audio compartment assembly. The following Hollowstate articles were helpful (thanks to Al, W8UT for the pointer).
I also replaced C170 across the Ext.mod in / audio out BNC.
The operation was a success.
In the middle of having fun
All done and enjoying it playing old tunes through the SX-16