yep! nothing left to do now, but get those hands dirty these folks on amiga org., has given the best advise. i'd go with the off board battery, i did this on my a500 expanision card about 4 years ago no problems. need to throw them barrel batteries in the trash. seems like i took small wire cutters and cut the battery from the legs and soldered my wires to the tip of the legs. don't forget to use acid free solder.
