When you say \"battery cover\" what exactly are you referring to?
Do you mean, you are pulling off the E1 drive booster and replacing it with the battery/grip holder that screws into the open area under the button? Is that \"battery cover\"?
Or do you mean, you\'re searching for the small, round metal screw-in plate that covers the drive coupling when the E1 isn\'t attached?
Or, is it the case that fits over the E1 terminals when exposed?
I\'m not clear on just what you mean, and am fairly familiar with the EOS-1 and 1n.
Obviously, option 1, the battery/grip would be more expensive and potentially more difficult to find.
Call Canon USA\'s parts department. They have schematics for most any product, even old, unsupported ones. They\'ll let you know if it\'s still available.
Alternatively, try somebody like KEH. If worse comes to worse, you could buy a \"beater\" of an EOS-1 or E1 and then swap out the parts you need. Assuming you can\'t source them otherwise, or for as reasonable a price.
