Most likely not an open IF coil unless there was some kind of physical damage or catastrophic failure of something else. You can test for continuity without unsoldering the coil. Best bet is to signal trace starting at the picture tube and working your way back. Old television repair books have some very useful tips. If you don't have a signal generator or scope one dirty method is to attach one end of a .1 630 volt cap to one leg of the heater string and poke along the circuit with the other end. It will introduce a 60hz hum into the circuit you can see on the screen. When you get past the defective component you won't see the hum bars on the screen.