i just used a butane torch to get the solder to melt and when i intalled the fdv v5 it of course leaked...bummer.so now gonna try the varitube with the dbl nut fully threaded 510 screw and see if using a ring terminal on the + wire and two nuts on the pin to make the pos connection work.../.?
I have 4 of these new varitube ones on its way to try out due to the same thing. FDV v4 and v5 leak.
I will be setting it up the say way.