41 steering box question

[oswego37]

After adding 600W oil to the steering box on a 1941 ford, knocked a small bolt in through the filler hole. Cannot retrieve with a magnet. There are 4 bolts that hold the cover on which I removed. Was hoping to be able to remove the cover to get at the bolt, but is still being held in place. Any suggestions on being able to access the inside of the gear box would be appreciated.