try a magnet on the pillar. If it sticks, it is iron.

I thought magnets would stick to magnesium, but some quick researching reveals that they do not.

Yes, a magnet sticks, it is definitely iron.

I accidentally dented the NEW motor tire and have to order another one, lol. Other than that, just to update, this machine is now in perfect working order as far as I can tell. I have done some sewing on it, although I am very bad at it! Maybe I should take a sewing class.

Glad it is working well for you now, except for the motor tire. Oh well. I haven't messed with the tension on mine yet. Your experiences may help.