2003 Honda Element reverse light problem passenger side

So went to get inspection and he tells me cracked tail light and no light for reverse light passenger side, no problem right. I order new casing along with new bulbs however when I put it all back together the reverse light and the reverse light only is getting power intermittently or whenever I wiggle something the right way so I am assuming its not a fuse and must be a wiring problem. How would I go about testing what wire is bad without going through the entire car? Also could it be the fitting thing that the bulb sits inside?