4 way hazards only flash in front

getting 69 dart
ready for state safety inspection and hazard lights acting funny...1st they didn't work...replaced flasher and passfront worked (coincidence perhaps but it was a new bulb).

put old flasher back on and both fronts flash but not the rear.

tail, break and turn work fine

ever happen 2 anyone else...I'm thinking the toggle switch may be on its last legs?

any ideas
thx in advance
steve