If the original coil didn't have a diode then you shouldn't have one on the new one. Plus, your wiring is backwards. The purple wires are the 50v. With no diode that doesn't matter but when the diode is there, if it's the wrong way, it causes a dead short and will probably blow a fuse if not the transistors as well.
Coils rarely go bad. As long as the resistance on the old coil is fine then it doesn't need to be replaced. Weak pops are usually a result of a switch that is gapped too wide, or misaligned spoon. Less often the spoon can be dirty, or the mechanism might need a rebuild