Once again, the cross/crown symbol was removed from the WT cover in 1931. Have you found an illustration with Jesus on a cross after that year? I checked my books and nada after 1931. It is just that the explanation came out in 1936. The Bible Students used to wear a cross/crown pin and were asked to turn those in about that time (1928) as well.
***yb75 pp. 148-149 Part 2—United States of America ***
Another change in viewpoint involved the "cross and crown" symbol, which appeared on the Watch Tower cover beginning with the issue of January 1891. In fact, for years many Bible Students wore a pin of this kind. By way of description, C. W. Barber writes: "It was a badge really, with a wreath of laurel leaves as the border and within the wreath was a crown with a cross running through it on an angle. It looked quite attractive and was our idea at that time of what it meant to take up our ‘cross’ and follow Christ Jesus in order to be able to wear the crown of victory in due time."
Concerning the wearing of "cross and crown pins," Lily R. Parnell comments: "This to Brother Rutherford’s mind was Babylonish and should be discontinued. He told us that when we went to the people’s homes and began to talk, that was the witness in itself." Accordingly, reflecting on the 1928 Bible Students convention in Detroit, Michigan, Brother Suiter writes: "At the assembly the cross and crown emblems were shown to be not only unnecessary but objectionable. So we discarded these items of jewelry." Some three years thereafter, beginning with its issue of October 15, 1931, The Watchtower no longer bore the cross and crown symbol on its cover.
A few years later Jehovah’s people first learned that Jesus Christ did not die on a T-shaped cross. On January 31, 1936, Brother Rutherford released to the Brooklyn Bethel family the new book Riches. Scripturally, it said, in part, on page 27: "Jesus was crucified, not on a cross of wood, such as is exhibited in many images and pictures, and which images are made and exhibited by men; Jesus was crucified by nailing his body to a tree."