I don't think this is from '78 as the Deep Action Agitator was used on the 65-69 Rollermatics. I've seen this ad before. Mark (Lightedcontrols) mentioned once that he had one of these back in the day. To find one would be like Gold.
Sorry, June 14 1968 Time Magazine. Cover has a pic of RFK running on the beach with his dog, just before he was assasinated. I can only dream of finding a set like that. Wow.
One of the few 69 Rollermatics to come with the variable speed clutch, allowing an infinite speed for both agitation and spin. I can't imagine that it was too terribly reliable.