We claim the ornamental design for a magnetic stripe reader card stabilizer, as shown and described.
FIG. 1 is a top, front, left perspective view of the claimed design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left elevation view thereof;
FIG. 5 is a right elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings form no part of the claimed design. Broken lines formed by equal length dashes show unclaimed subject matter.