no need to remove the armrest.  simply drill one hole in the bottom of  the 
seat rail into the mount bracket and insert a self tapping screw. 
 
 
In a message dated 9/29/2016 6:56:38 A.M. Eastern Daylight Time,  
ecaron1@COMCAST.NET writes:

Perfect!  I’ll try  removing  the arm rest first and drilling  new holes 
second.  thanks for the great info.  this was just what I  needed.