It was a technically very troubled concert. Yes at the time were carrying a quadrophonic P.A. system (at least this is what the music press reported at the time with an unheard before emphasis about it), and the concert was to be performed at Rome's "Palazzo dello Sport" (Sport Palace or Sport Arena, if you prefer), a steel and concrete building well known for not being exactly designed also for musical events. They apparently had a lot of trouble in setting up the P.A. system and in the late afternoon all of Wakeman's mellotron passed away! The promoter and the tour managers scrambled throughout the whole city raiding all the mellotrons available in order to have them ready for the night gig. (Can you imagine the scene: "Hey pal, have any mellotron in the house?" "Yes..." "Well give me three, please, and quick, I have a Yes concert in the other side of Rome in two hours!") As happens in the fairy tales all pieces fell together in their right places and the gig was extremely well received and still remembered.
I remember the two minimoog of Rick were out and a music store has provide with others two in few time.