The ornamental design for an exercisemachinecoverplate, as shown and described.
FIG. 1 is a perspective view of my exercise machine cover plate, showing in dotted line the field of application for illustrative purposes only and to which no claim is made;
FIG. 2 is a front perspective view thereof with the with the dotted lines showing of apertures being for illustrative purposes only and to which no claim is made;
FIG. 3 is a front view thereof with the back view being a mirror image thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a left side view thereof; and,
FIG. 7 is a right side view thereof.
The portions shown in broken lines are for illustrative purposes only and form no part of the claimed design and to which no claim is made.