To all who replied, many thanks.
I resolved the issue this morning in about 15 minutes.
For others here is what I did.
1. Close intake seacock
2. Remove intake hose from seacock.
3. Remove intake hose from rear of toilet
4. Fill the hose with water and run the electric motor
. Hold the hose over the bowl. This causes the water to be discharged from the hose and clears the air lock.
5. Reconnect hose, open seacock and use normally.
But I still don't know why a pump-out caused this. Yes, a note to Peggy would be good to do, but I thought she was out of the business.
Now where was I....ah yes, cleaning