VN0350N1: Vg=-3.6V and Vs=0V
VP0350N1: Vg= 4.1V and Vs=0V
Assuming that you have mis-typed the VN - VP designators, then yes, the voltages are in right ball-park. Since you have replaced the output transistors I would expect that the biasing needs adjustment (the 5k potentiometer), however, this would not prevent the output from working (but it might be distorted or the transistors might run too warm).
Can we assume that the fuses are intact and that the +- 220V is reaching the drains of the mosfets?
How are you measuring the signal waveforms - do you have access to an oscilloscope?
What is the signal level at both sides of the 100R in series with the output?