If you used the 'A' type log pots for the volume, you shouldn't be getting that on/off volume. It sounds a bit like like you've swapped the volume and tone pots.

I presume the pots work in the normal way, so that maximum volume is fully clockwise? If it's not and maximum volume is when the volume pot is fully anti-clockwise, then you've swapped the two outer pot connections over and the pot is working backwards so a log pot would now have an anti-log characteristic.

Did you take any pictures of your wiring harness before you fitted it?