Watching the early Barnabas episodes , it surprised me that they would announce the change from the first Dr. Woodard (Richard Woods) to the second Dr. Woodard (Robert Gerringer). Woods appeared in only 2 episodes somewhat apart from each other and the audience wouldnt have been that identified with him in such a small role at that time to be informed. The first time I saw DS, I didn't remember the first Dr. Woodard at all.
When they recast Lt. Riley during the Laura story, there was no annoucement, even though the change occured the very next day. I would think in that case, there should have been some announcement in the actor change. The second actor was better, the first was too New York sounding.
The same for Harry Johnson. Craig Slocum had the role for several months and was prominently featured for a while. Yet there was no mention made of the new actor (Edwrad Marshall) replacing CS during the opening credits he first took the role over in.
Matthew Morgans recast didn't get announced but Sam Evan's did.