LongArc,
First of all, any welding machine with the brand name of "HOLBART" is most likely not worth the sticker that is on it.
However, HOBART makes some high quality welding machines.
None of this matters in your situation. I can promise you that the "brand" of welding machine you are using has nothing to do with you receiving a jolt.
So in short, it does not add up. There is something that you are missing.
I am very interested in, helping if I can, and for sure, the answer that you end up with.
Many possibilities.
BTW, there is now a "Safety" site and this is something, IMHO, that should be posted there as well as here. I usually would not promote double postings, but in a few situations I have seen it result in twice the valuable information.
Getting zapped has always been high on my list of safety concerns.
John
EDIT: Having said that I must clarify. There may be something wrong with the machine itself, but unless this is brand new out of the box, something is going on that would not be effected by what brand the machine is.IMHO