There seems to be a failure rate of these in days (like most electronics) right out of the box.
Returns are a problems, expecially if you mail ordered them. There are other questions in this forum on how hot these should get.
Make sure they have ventilation and I would stand them upright, creating an air tunnel through the case.
I installed a small PC fan in my Maxtor OT4. Now it's much cooler at the base.
I just think it was not built right and toasted. I have another Maxtor that was running scandisk for hours with no problem.
I've seen many other external cases made by other companies, a few with fans built into the case.