The ornamental design for a western blotprocessor, as shown and described.
FIG. 1 shows a front left perspective view of the western blot processor;
FIG. 2 shows a front right perspective view of the western blot processor;
FIG. 3 shows a left side perspective view of the western blot processor;
FIG. 4 shows a right side perspective view of the western blot processor;
FIG. 5 shows a right side view of the western blot processor; and,
FIG. 6 shows a front elevation view of the western blot processor.
The broken lines in the drawing views are included for the purpose of illustrating a portion of the western blot processor that forms no part of the claimed design.