I'm telling you, I think you have the dot convention on your coils wrong. The dot indicates the "start" of the winding. Since you are trying for a plain centertapped coil set, the center tap should join the END of one winding to the START of the other winding. The way you have it, you have the center tap connecting the STARTs of both windings.
Look at my LTSpice simulation below. The _only_ difference between the two schematics is the way I have the coils oriented wrt the dot convention. In the working version (Righthand panes) the center tap connects the dotted end of one coil with the non-dotted end of the other coil. One way works, the other way shown in the LH panes (the way you have it) does not.
So... reverse the connections of one of your coils and see if it starts working. This is something that all JT builders know: If it doesn't work at first, reverse one of the coil connections.