I'll chip in as best I can.
As I see it there are 2 trim pots with a phillips head cross in the top of each and two roller pots with a centre line on each.
The top trim pot as you look with the bass upright controls the overall output of the bass, and with the pot all the way up has tons of output (and I am comparing this to some of my other basses with J Retro pres, Bartolini pres). The bottom trim pot controls the amount of boost or cut for the mids. The two rollers control the centre frequency for mids, depending on what position the external mid knob is selected(see my second pic - you should be able to see what the external knob says - MID BOOST, MID CUT AND OFF(flat).
Hope that helps. Even with this knowledge you still really have to set and test different settings to find your tone. FUN.