Class AB Amp Distortion / Repair
The amp seemed to work perfectly with the wire replacing the diode

Most likely explanation:
The opamp can power the transistor's base through the wire, but not through the diode, which is in the wrong direction. As you noticed, this points to one of the resistors between the transistor bases and the supplies being open circuit, so no current flows in the diodes, and they can't do their job. So you can check and replace the resistor.
With the wire instead of the diode, it will increase crossover distortion since the opamp has to yank the bases by 0.6V every time there is a change in current polarity.