wrote

Thank you Gentlemen all very good info. I didn't have to call the
plumber yet. It looks good when I flush the "Disposal unit" with hot
water before the dishwasher starts, no back up at all. I am thinking
of removing the "disposal unit" out of the system and it will please
the Wife.

Grin, glad to help James. The hot water trick means there is some level of
build up, probably in that pipe I mentioned between the 2 sinks.