Gain control on Ruby amp.

[DrifterCBG]

New to all this. Finished my Ruby amp build. Added a tone control from the Noisy Cricket design and also the two way switch (voice?) control. Fed into an 8", 8ohm Fender speaker. Really nice little amp. One problem. The gain control does not kick in at all until (on a scale of 0-10) I crank it up to about 7 or 8. I originally used a B1K pot, then put in a B10K pot. No difference, gain still has nothing until 7 or 8. Would like to have linear gain that starts at 1 and builds to full at 10.  Running off a 9 volt AC adapter.   Any suggestions as how to get this the gain to work better?

[Jazz P Bass]

It seems to me that the gain control is in the feedback path of the output ic.
https://robrobinette.com/How_the_Ruby_Amp_Works.htm