Assuming that NTE part is the correct replacement part, it sounds to me that your driver is out as well. OR - that the bias needs to be adjusted on both the driver and final transistors. Another possibility is that there is a diode somewhere in the output that has failed as well.
I would surely check the biasing of the driver and the final - first - IMO. Generally speaking, when you see backwards modulation on the output, it is because the driver or the final bias is set too high. This can also quickly burn them out once again. I am new to working on radios; but that has been my experience...