I am new to this. Just got a used Whites 5500 D series 3 from neighbor today. Downloaded manual. Opening the battery box was so difficult I worried I was going to break it! Is this normal? I had to get fingernails in the gap and actually pry it open to allow the little slots to get the pins lined up and out. Luckily old batteries not corroded (4 C's). Too cold to do anything outside yet. Found this site, and thought I'd join. Any advice would be great.