Šlitr wanted to play and compose in a modern "rock" style at the Semafor but Havlík disagreed. In 1966 Šlitr fired the "Ferdinand Havlík Orchestra", but in the end he wound down his own involvement with the Semafor and with Suchý. The duo parted company for a short time, and Šlitr put on a new play "Ďábel z Vinohrad" (The Devil from Vinohrady). Meanwhile he exhibited his drawings in Wiesbaden, Dortmund, and New York City. In 1967 he attended Expo 67 in Montreal, where he presented the show "Stars of Prague", and during his stay in America he exhibited drawings in Hollywood and Houston. In 1968 he reunited with Suchý and after the events of the Prague Spring he restaged his earlier work "The Devil from Vinohrady" as a pointed response to the Soviet invasion of Czechoslovakia. Šlitr and Suchý also signed the anti-communist 2000 Words manifesto by Ludvík Vaculík. In 1968, Šlitr appeared in his last film, "Zločin v šantánu" (Crime in the Night Club).