E1 socket not working

Hi

Total 3D printing newbie here, apoloies in advance if my terminology is wrong.

I have a dual head K200 delta printer with a heated bed which I put together 8 months ago, but gave up due to frustration of the following error in Repetier:

temp sensor defect marked defect
Errorrinter set into dry run mode until restart!

I've tried again today, and all 3 thermistors (and the spare) work fine, but socket E1 on the BT7200 V1.8.26 RAMPS PLUS 2 is giving me -20oC readings no matter which thermistor I put in.

Even though I’ve tried to tell it there’s only 1 extruder (in Printer Settings), the display right at the bottom of Repetier still thinks there’s 2.

I've emailed the seller and the company I bought it *through*, to see if they can help.

In the meantime - is there any way to change things so that I can use the heated bed socket for the other extruder instead and just try to make due without the heatbed for now?

Hope you can help.

RAMPS PLUS 2 and E1 socket problem (K200 Delta, but related to the PCB , not printer)