Bump-a-titty bump-a-titty: Here you go DL: that be your Bart Maverick amp in the pic below:
Your amp has 'ganged' volume pots controlling volume. Interesting; in the 2-channel / 4-preamp tube bass heads, they added a master volume control allowing the preamp to be turned up to overload and then turned down allowing more variability in tone. In your amp, both gain stages are upped and downed at the same time.
The schematic above is a little confusing; at the far left, it says:
Volume 1M (1 meg) 10% LOG but on the right it says:
Volume LIN. (in both cases, the 004027 is Guild's part #) Pots are usually either 'audio taper' a/k/a logrithmic or 'linear'. The schematic suggests that the 1st stage is 'LOG' or logrithmic (audio taper) but the second stage is 'LIN' for linear.
Both dual 1 meg audio and linear taper pots are available but I can't say that I've ever seen one of each type ganged together - oh those pesky Guild audio engineers .... :evil: The only thing that makes any sense is that they were trying to keep the last gain stage/driver/output tubes from being overloaded; while the 'front' half of the pot was allowing more volume (dumping less signal to ground), the other or back half is trying to 'meter' or more carefully control the signal seen by the output section.
In any event, why don't we wait on default, Kap'n, Teleharmonium or one of the other solder-heads and see what they have to say before doing anything else. cj