how do you change file path for imbedded image

I have several dwg files with an embedded tiff image file. The embedded image is looking to the wrong location for the file but I am unable to rename the path in the properties. As long as the dwg and tiff image are in the same folder it will find the image when opening the dwg. If I try to create a pdf from the dwg all that shows in the drawing is the wrong path to the image file.