Horrid Mike McGurk Replacement

Does anyone know why Smiley Burnette didn't return as Mike McGurk?

Lee Ford displayed some of the worst acting I've ever seen and almost single handedly ruined the entire serial.

I wasn't a fan of the Junior replacement either, but at least that wasn't detrimental to the enjoyment of the show. He was simply annoying and unlikable.

I also own SOS Coastguard, but I haven't watched it yet. I'm hesitant now, since I see Lee Ford is in it. His acting really is that bad.