Find the positions/bookmarks of the object
Identify the positions/bookmarks by executing the below query on the KB -
select Info1 as "Start Line Number" , Info3 as "End Line Number"
where idobj = <object_id>
The decrease in KLOC could be due to incorrect storage of the start & end positions of the object due to which there may be overlapping and loss of KLOC.To confirm the same you can check the Start and End position of the object by looking directly into the source file.
To verify this you may also connect to enlighten, drag the object on the view and hit the F11 key to view its source code and the F12 key to view its properties. This will show the number of lines of code for that object and the actual source code highlighted.