Wire on my Mark 1 Suitcase leads to nothing

[thegetawayplan9]

Hello,

So I have been trying to resurrect my 1975 Mark 1 Rhodes Suitcase. To this point I've only been able to use it by using the FX loop output. I notice the FX loop has a wire coming from the preamp to the fx loop that is attached to nothing. What does this goes to? I haven't been able to find a schematic for this. Photo of the lose wire.

[Ben Bove]

The accessory loop is basically a break in the connection to insert effects pedals.  So, imagine the grey RCA cable at both ends here being joined together, if there was no accessory loop.

I can't tell exactly from the picture on what the solid white wire is doing, but ultimately - the clear insulation wire that's going to nowhere, probably is the signal off the harp. 

This video shows how the effects loop works, so you can retrace your wiring there according to this.
https://www.youtube.com/watch?v=68dM_6FU_Pc