ok so im goin to go check out a 95 ninja zx750 tomorrow and guy says i just need a battery . he tells me he bought it off a friend and only had it for 3-4 months , went away for a few weeks and came back . went to start the bike and the battery was dead . also said he took it to a machanic and machanic stated that new battery was needed . he's selling for 1800 . what other possable issues may there be ? r/r ? ground ? plain o' battery and hes just to lazy to get one ?