Status of episodes...
I know there are several posts here pertaining to what's available and what's not. A good chunk of the 60s run is extant, but many of those were from the nighttime version; the daytime version is thought to be largely lost.
The ABC run is rumored to have been wiped, which was something that ABC routinely would have done during that period - there are a few episodes on the trading circuit, most which are also on YT. One is a December 1971 episode with Brett Somers and Jack Klugman, another is from February 1972 with Sheila MacRae and Martin Milner. There are also three known later episodes: with the "All-Stars" Grandmaster Tournament Finale (Betty White, Hal Linden, Richard Dawson, Bill Bixby), an episode with Betty White and Vicki Lawrence, and the finale with Kate Jackson and Sam Melville, in which Betty appears with Allen at the end, and all three of those are from 1975. There may be other bits and pieces of that run out there that were taped by home viewers, or possibly something in a vault somewhere, but the whereabouts of any of those are unknown.
Hope this helps! :)
"I love acting. It is so much more real than life." - Oscar Wilde