Crap, so you have the issue of ReConstructing the area where the 510 was and soldering the Negative Battery lead back onto the board.
You know as well as all of that you probably won't get the Negatvive Wire soldered back on without removing that board to do it properly. Are the Boards just slotted in or screwed in? Also I imagine if you remove the back board you will have to remove the front board too! Man what a PITA!
As for the 510 connector you can visit the previously mentionted website or go to Madvapes and then there is the for evr more website Fasttech and you can't Not find a 510 connector with screw in back end to keep it put. Just make sure it is glued in so it won't spin.
I'm surprised that those Mods are made that way.
Also, I wouldn't be looking forwars to pulling out that rear board to solder. Is there a way you can just pull it out about a half inch.
Further, ESD or Electro Static Discharge? I wouldn't really care at all about ESD with farting around with an eGo fix but what you have there has plenty of bits that can burnout if you shock the Mod with your hand. I would in the least work on the Mod in the garage standing on concrete and touching something like a Radio that is plugged into a wall socket to discharge any charge that you may have accumulated from walking around on carpet etc..
My last job working on computers we would in the least touch the power supply to discharge or touch a coworker. Wouldn't think that last one would work but it does.