The ornamental design for a slotmachinecorkholder, as shown and described.
FIG. 1 is a front, right side and top perspective view of a slot machine cork holder showing my new design;
FIG. 2 is a back view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a left side view thereof; and,
FIG. 6 is a right side view thereof.
The broken lines define the bounds of the claimed design as well as depicting unclaimed portions of the design. The broken lines form no part of the claimed design.