LSTE522 - 20V MAX* EASYFEED™ Electric String Trimmer/Edger With 1 Battery

     I received LSTE522 String Trimmer from Black & Decker company as a replacement for a Black and Decker model no longer being made. When trying to install the guard part I am not able to slide it fully in place as shown in the owner's manual. I am concerned that too much force may break the part. Has anyone else had this issue. I contacted the company and received the reply they are sending me a new guard part, not on how or why the original part is difficult to install.