Help with overdrive circuit; clipping stage!

[Twotoneskaman]

this is the clipping stage of an overdrive circuit i have been building. the problem i am having is that when you vary the pot it only varies the "overdrive" when you first start turning it, the waveform then remains the same across the rest.
I was wondering if anyone can see anything really obviously wrong with the circuit?!
would be grateful for help!

full circuit can be seen here:
http://i45.photobucket.com/albums/f97/thenobbit/circuitweb.jpg

[$uperpuma]

another taper of pot might work better...

[stm]

Yes, using a 1M Log or Audio pot should do the trick.  Also, you shouldn't connect to ground the right side of the pot (as shown in the schem), otherwise at maximum gain you will be shorting the opamp to ground and have little or no output at all.  Instead, try lifting the right side (clockwise terminal) of the gain pot and short it with the middle or wiper terminal.