Figure 1. Dual slider pot.
simulate this circuit – Schematic created using CircuitLab
Figure 2. Standard wiring.
- You should be able to measure the pot's resistance between 1 and 3.
- Resistance between 1 and 2 should vary from zero when slider is towards 1 and maximum when slider is at 3.
Using linear taper on audio will result in nearly all the significant volume change occurring in the first 10% of travel. It's usually a terrible idea.