How to find the location of interference source?

Dear Experts,
One of my 2G cell is having poor IC HOSR, Call Drop rate and indoor coverage complaint. We suspect interference, how to find the source of interference’s location. Tools available TEMS Investigation 19.1 with IBflex scanner.

Move the antenna azimuth to establish an orientation where interference is most. Do the same on two neighbor sites. Now draw a line from each sector and see where these three lines cross each other to locate the interference source.