Miller Electric CST 250 Owner's Manual page 29

Trouble
Erratic or improper weld output.
Wandering arc
Tungsten electrode oxidizing and not
remaining bright after conclusion of g g
weld.
Possible Causes
Weld cable too small or defective.
Dirty or loose connections.
Improper size tungsten.
Worn or defective tungsten.
Shielding gas flow too high.
Shielding gas blown away from weld
zone.
Inadequate postflow time.
Loose or leaking gas fittings.
Water in torch.
Remedy
Use proper size and type of weld cable (see Section 3-6).
Clean and tighten all weld connections (see Section 3-6).
Use proper size tungsten (see Section 7).
Use properly prepared tungsten (see Section 7).
Reduce shielding gas flow rate (see Section 3-7).
Shield weld zone from drafts.
Allow adequate postflow time to shield tungsten while it
cools, after welding stops.
Check and tighten all gas fittings (see Section 3-7).
Refer to torch manual.
OM-2237 Page 25