One of your heads is coming in oversized. All others seem to be fine.
First, delete the oversize head symbol. Then type PRG in the Command line and press Enter to purge it out of the drawing.
Now open the Irrigation Manager.
Highlight the problematic head in the Irrigation Manager (example: Rainbird 1804-SAM-PRS), then click Delete to delete the head from the project.
The system should automatically re-link with all the other symbols that have already been placed. To be sure, place the head again to make sure it looks right.