ROLAND VS 1680?!?!?!?!?!?

[Dead Dawg]

My band is working on a rough demo with our roland vs 1680 and we were recording a drum track and the drummer wanted a re-take....so we put it back to zero to overdub over the old drum track. when the counter reached about 2 seconds it said disc memory full....now if we just recorded 3 minutes of drums before that...how come its full now? so we completely erased the old drum track. Yet again at 2 seconds "Disk memory full" came up again...I came to a conclusion that it was saving the old overdubed tracks...is it doing this? does anyone know how to fix this problem and does anyone own the machine and still have the manual....

Any help would be greatly appreciated

Thanks
Dave