Here's a couple of pictures of The Monkees on the set of Hollywood Squares in December 1968 (filmed right after Peter Tork had left the group). The first photo shows the trio backstage with Jo Anne Worley, Peter Marshall, Judy Carne, and Henry Gibson. To date, no video of this appearance has surfaced.
A NBC press release announcing The Monkees' appearance on Hollywood Squares:
In Memoriam: Michael Nesmith
Dolenz sings Nesmith - The EP
Micky Dolenz Live!