[JThiessen]

I'm kinda thinking the flux might get in the way of a good joint on these. There is no side hole on the EC5's, so when you add flux (and yes, I'm also using flux core wire) you basically end up with this molten pool of solder with a layer of flux sitting on top. You then stick the pre-tinned wire into that pool and let it sit until it solidifies. I'm thinking that maybe that layer of flux might create a "protective" layer around the wire, preventing the solder from bonding....