The ornamental design for a bufferingmechanism for an extension ladder, as shown and described.
FIG. 1 is a perspective view of a buffering mechanism for an extension ladder showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is left side elevation view thereof;
FIG. 5 is right side elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines shown in the figures are for the purpose of illustrating portions of the buffering mechanism for an extension ladder and form no part of the claimed design.