Your voltages are all in the right ballpark so you have the same headroom as the original.

Turn R2 down to zero, then put a 1kHz sine wave through the amp and a 680 ohm or similar on the output, sub your 22k pot for the 10k res and set to 10k. Then note the height of the sine wave on the scope as you wind up the input. When it starts to flatten, try adjusting the pot back and forth to see if the sine wave sharpens up again, adjust for best shape and maximum height. Then carefully remove the pot and measure the resistance, find the nearest value and solder that in.

Now start to wind up R2 and see if the waveform changes. Then do the same with the next amp and compare outputs. This exercise will show up any problems in the output stages. This is how you track down problems with a careful process of elimination. Keep a note and post any differences between the amps.

best

DaveP