Strange GTAW Aluminum Problem

I Say strange, but its new to me..

1st off, I'm still 'new' to Al welding, but I welded this telescope project together without any problems:

However, I welded that project together with a Miller Syncrowave 350 that I had access to. To save myself the drive, I purchased a Miller Syncrowave 180SD.

I'm welding the same materials, using the same sized filler, tungsten, cups, current setup, and shield gas as I did on the 350 machine.

Anyway, here's a few pictures of the problem:

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In the first image, I've circled the problem areas. The items labeled

1 & 2 are created (repeatedly) by doing the following:

#1 Strike an arc #2 Wait till metal looks shiny #3 Touch filler rod to shiny spot #4 Instead of joining the 'puddle' the filler rod creates a ball of metal #5 Once it does this, the ball just sits there and creates more slag the longer I try and heat it.

On Item #2 I tried 'Forcing' the ball to go away by fully depressing the control pedal, with the amp dial set at 125 amps AC. All it did was make more slag..

On Item #3 I stopped for a moment, then tried to restart the bead.

When I used the Miller 350 machine, I NEVER recall having this problem. Sure on occasion I'd make a ball at the beginning of a weld, but adding some more heat always made it join with the base metal. Now adding more heat just makes more slag. When I first saw this phenomenon, I thought I forgot to turn the Argon bottle on...

Anyone have any thoughts?

For the record, here's the detail's on the materials and setup.

Base material is 1/8" wall, 2" square tubing from local hardware store

Filler rod is 3/32" 4043

Tungsten is 3/32", green tipped pure tungsten

Using a #6 gas cup (also Tried a #7 with same results)

Shield gas is 'Pure' Argon, set at 25 CFH

Torch is a 150 amp air cooled unit that came with the machine

Machine is a Miller 180SD set at 125 amps AC on the dial, and the Clean - Penetrate knob is set at 4 (on a range from 0 - 10, with 0 being more cleaning action, and 10 more penetrating action)

Here's a list of things I've tried:

More Argon flow, Less Argon Flow Close all doors and windows in the shop, make sure there are now fans running, nor any drafts.

Fresh Tungsten, Gas Cup, and Collet

Wire brush the crap out of the base metal with a new stainless steel wire brush cup in a 3/8" drill

Played with the Clean / Penetrate knob in all kinds of positions.

Take Care, James Lerch

(My telescope construction, Testing, and Coating site)

Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge