Mike,
The battery holders sort of swing up and out. Position the MB-1 as if the
lens was pointed down. Open the compartments and focus your attention to the
right side battery holder. Now, look on it's right side and you will see al
"grippy-thing". Put your finger on the "grippy thing" and pull up while
applying pressure to the "grippy-thing" to keep your finger from slipping (I
believe the "grippy-thing" looks sort of like some shingles). The battery
holder will be difficult to get moving, but once it starts, it should come
rith out. Good luck.
Brian Wermeyer