After you have beten Drek and you have either started over or have gone back to last safe go to Gremlik base and defeat Quark. Do NOT go into your new ship if you are starting over. There wil be a tower to the right facing down the runway. Go to it. There should be a passageway that goes all the way through. Right after the passage levels off start doing wall jumps. At the top there is a platform with a button. Hit the button and it will take you to the top of the tower with all of the gold weapons cases.(Note: The weapons in there are the ones that you havn't gotton already.)