Roland TR-808 no memory when power off

Hi all,
I bought a used 808 in the 80s that had already had a bit of a hard time. It all works, but there looked to have been a battery leak. I changed the battery compartment and cleaned it out, but it has only ever kept note memory for less than 48 hours with fresh batteries. It works fine powered on, but once you power down, you lose all your beats after a few hours. I can only guess power from the batteries is leaking out somewhere, but how would I know? Has anybody ever had a similar problem or got any ideas?