Are any board traces cut? Is the chip in the disk drive a FD3206 or a FD7201?
I don't know what the mod is, but a copy protection mod wouldn't have a switch on the back, let alone a 6 bit toggle switch. Where does that red toggle go and is that LED next to it on all Twins?
It appears that 2 blue wires are not connected or one or the other fell off the solder point on that 6 bit switch, though...hard to say. It appears only 5 switches are used with a space between the first switch and the other 4. I'd have to bust out my Backup technique issues and look...It wouldn't be in any Gamlabs...it would be within probably the first 10-14 BT issues. What month of what year did the Twin come out? That may save me from looking through a few issues. I still have a bunch of old copies for sale, BTW.
shameless plug ftw.
If I had to guess, it is a dubbing circuit. Is that a potentiometer on the outside or another LED? The LED(s) and knob is used to sync the two machines together, iirc. However, if that's not a knob, then I have no idea, and I still really have no clue what the switches are for (EDIT...never mind, that's the disk power LED). Why would one want to switch between 32 states of anything on a FC? Or, if the first switch is just to denote whether the mod is "On," and then there's 16 states of something. I dunno.
-Rob