This is my first attempt at 1/4" aluminum outside corner joints. Running 200amps, 100 hz, 40% balance and 1/8" tungsten.  After successfully welding out most of these mirrored 3 sided pyramids, I all of a sudden on the last half of the last weld had issues with blowing a hole in the outside corner joint. I let it cool, ground and cleaned the damaged area and tried again. Because of the increased width of the weld joint I decided to weave, but as I got close to meeting up with the previous weld things went sideways on me. Erratic arc, very hard time forming a weld pool and lots of porosity. Pictures are attached. Any advice would be greatly appreciated.