I have had the 6600 since 2008. Love it. The term Workhorse has been used since it was first introduced. It is heavy,to me, but it is all metal, which probably accounts for its durability. I make bags and it has never disappointed me. I would ask the seller when the last time it was in for a check up. Since it would cost you 75 to100 dollars for a check up, would they consider $350.....but I would buy it in an instant at $400!
If it runs, buy it.