maybe drill a hole & bend a new tab on what's left?
Oh, and are you sure it's "kosher" to lie the battery down like that?? Every "maintenance free" battery I've ever had has 1) removable caps to replenish water (although it seems not many folks actually do that), and/or 2) a vent on the top/side to allow gas to escape. If it were me, I'd put it upright.
Brent
