I have a Rowenta DM880 that I have been working on. Removing the back plate to access the cord was also a problem for me. In case your model 330 is similar, here is what I did.
The fasteners used by the manufacturer are two modified "torx" head screws. The 'modification' is a small pin in the center of the torx head which prevents the use of a normal torx driver.
I took my vise-grip tool and clamped two finishing nails side-by-side into the jaws. The nails extend straight out the end of the vise-grip (in line with its longitudinal axis). Then I simply inserted the tips of the finishing nails (now firmly clamped side-by -side) into the head of the fastener. The tip of the nails straddle the previously mentioned "small pin". At the same time they are seated into opposite corners of the torx head. And with a gentle amount of torque the fastener came out easily. Installation if the reverse.
Good luck.
Ken
Ken
November 2005