Jon, I will do a little practice welding next time.
Alvy, I think I checked the polarity the last time I used it but I will double check it again. I didn't look at the rollers or check the tension either and now that you say that I don't think the wire is feeding consistently.
I will check that too.
This machine came to me from a mechanical contractor that owed us money so there is no telling how much use it had or any maintenance had been done to it.