Thanks for tip! I've been given a few tips from welders at work. First and foremost is the metals need to be clean. Didn't think about the soot contaminating the joint. Their other tip (especially if TIGing Aluminum) was to pr-heat the work with a propane torch or equivalent. I've got a Thermolyne electric hot plate that gets to 750 F (use it for tempering steel after hardening), will give that a shot before my next attempts!
Best regards, Bruce