Looks like he was on some type of Comedy Tour based on these appearances he made during February of 1976. The Rent party ep aired on 3/2/76 and the production date was 2/19/76 but looks like Jimmy had already decided to skip it due to some appearance the final week of February

Jimmy Walker made guest appearance on Donny and Marie........Feb 6. 1976

Jimmy Walker appeared on Game Show.."Rhyme or Reason" from Feb 23 to Feb 27th of 1976

Jet Magazine Issues of Feb 1976




Now I have to find out why he was missing in the season 6 episodes