Hi all. So I've got this old Bartolini NTBT preamp that was in an MTD Kingston 5 I owned briefly. It was installed without a gain trim pot, so the signal was wicked hot coming out of the bass. I replaced it with a new NMBT and later sold the bass, which leaves me with a perfectly good, albeit somewhat old, NTBT preamp. As it so happens, I've just bought a bass that has a nice Bart M4 pickup wired to a passive volume and tone and I'd like to put this preamp to use but am decidedly limited by my own lack of knowledge. I can solder with the best of them (or at least the pretty-good of them), but I'm not sure where one might acquire a gain trim pot or how to properly wire it in. On the plus side, there's a helpful diagram on the Bart site that shows a trim pot attached to three wires, a white one, a blue one, and a grey one, and between the white one and the gain pot there's a little bit labeled 1.3K-ohm which I'm assuming is a resistor. Armed with this knowledge I was thinking of heading over to Radio Shack and surveying the possibilities, but one thing is kind of worrying me...how do I know which wire goes to which prong coming off the gain pot? Can anyone suggest a better resource for parts and/or give me some help in wiring this up properly? Thanks very much, J.