>         1.  PIC running on +3V
Is your 16C622 rated for 3V?  Not all PICs are.  Try temporarily at
5V, then you'll know it that's it.

>         3.  Config word set as below:
> 2007 3FF3           00038         __CONFIG        _CP_OFF & _RC_OSC &
> _PWRTE_ON & _WDT_OFF
Make SURE you've re-compiled correctly for the '622 target.  The
bits in the Config word may be different, and the address of the
Config word may be different.

>         4.  Square wave visible on pin 15 (osc out) when using
16c61, but
> pin sits low with 16c622A.

Which proves the osc is not working right- wrong config burn is the
most likely reason, IMHO.

-Barry
------------
Barry King, KA1NLH
Engineering Manager
NRG Systems "Measuring the Wind's Energy"
Hinesburg, Vermont, USA
www.nrgsystems.com