Were you using crimped ferrules on the wire ends? Bare wires can loosen overtime and the increased resistance causes heat which can eventually get hot enough to melt the socket. It's also a good idea to tighten them up after a break in period, and again occasionally as preventative maintenance.
I think these may be the screw terminals you're looking for.
https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers#Section_Screw_Terminals
Perhaps post some detailed close up photos that show the extent of the damage. It's possible the damage goes beyond just the terminal. Though it's a good sign if the rest of the board is still functioning.
To remap the heater you'll need to move your thermistor connection over to E1 and the heater of course, then you'll need to change your M305 P1 to M305 P2 and your tool definition in M563 H1 to M563 H2 in config.g
Post your config.g and we can tell you exactly what you need to change.
