The piston that closes my storm door is slipping.

The problem is on the side that attaches to the door. There is a
bracket that screws to the door. It's a standard part; it has
openings so that it can be screwed into the door in various positions.
The problem is that the two screws holding this bracket in place don't
"bite" tightly into the door. I can pretty much push them in or pull
them out by hand, and if I use a screwdriver, they just spin and spin
and spin. So, not screwed tightly to the door, this bracket just
slips when the door closes, and the door doesn't get pulled tightly
shut.

http://www.naturalhandyman.com/iip/i/closeradjust.jpg by the way has a
photo of what I am talking about when I say "bracket" - that part on
the right with 5-6 overlapping holes and the screw in the fourth hole
from the left.

As my ignorant eyes see it, I have these options:

1. Get slightly larger (wider) screws, enabling a firmer "bite" in the
existing holes. Eliminates having to drill even more holes in door -
don't want it looking like Bonnie and Clyde car after all...

2. Since the bracket has several places where screws may go, just
drill a new hole in the door, same approximate real estate in the
door, and leave the bracket in the same position, just held down with
a different screw position.

3. Move the bracket a bit, drill new holes, use same old screws. This
may be an attractive option, because even though I have the piston
adjusted for the least resistance, the door doesn't always close all
the way. If I picked this option, would I move the bracket closer to
the hinges, or farther from the hinges/closer to the open part of the
door?

Comments or suggestions?