A friend has let me use his Lincoln Tig 300/300 (the later model, not the old timer) to practice on at his shop and we are having a problem in that the green tungsten won't form a ball. Even he can't get a ball to form. It does weld, but not as smoothly as it should. The arc can go along fine then it becomes finicky and wanders (looks like arc blow in SMAW). I'm practicing on clean (3M Roloc polish pads) 1/8 aluminium with 3/32 Weldmark electrodes using straight Argon at 15 cfh. I'm on AC mid-range, current range 7, with start "ON" (constant). I have no idea what those setting translate to in amps. The torch is a Weldcraft water cooled with a #6 collet (no gas lens). The ground is solid. I think the problem is in the electrode but even if I switch to a new one the problem again develops. Any ideas? Thanx