Leading Edge Disagree

Air return for "Leading Edge Slat" disagree EICAS warning. Flap indicator would not return to "0" when Flaps/Slats selected up after take-off.

The first item checked was Fault History on the Flap/Slat Electronics Unit. (FSEU).
  
     
     
  
The fault code description in the FIM was nondescript. It basically said.... yes, you had an issue.

We couldn't duplicate the problem. The Proximity Switch Electronics Unit (PSEU) showed "near" for all 24 prox sensors with the flap handle up and none of them showed failed.

The next avenue to pursue was to use LCR meter to measure the inductance of each sensor in hopes that one (maybe more) didn't match up with the rest.
  
     
  
Sure enough... one reading for "S279" the #4 outboard slat sensor was 5.2mH vs. 5.5 to 5.9 for all the rest. Out to the wing to gain access to,,,,.
  
     
  
After the lower external panel was removed.....
  
     
  
The target plate was bent out "away" from the sensor face.

Our first "persuasion" of the target increased the reading.....
  
     
  
The second attempt brought the reading in-line with the others.