Check to besure the locking pin is aligning with the hole in the battery pack. Also be sure you can feel the pack pressing down on the spring pins under the pack. If the pack is going down and it is a side to side alignment problem you can bend slightly as needed. The lock do tend to fail though. So simply tie the pack down from top to bottom. Use strong string or rope. Be sure you have the pack tight on the spring pins under the pack.

Replacing the lock takes about 3 minutes. Only 2 screws.


BTW, Doesn't the battery rack hold 2 batteries? Use the other side of the rack.
Bob