I bought (cheap) a GE StoreSafe from my boss and cameras that shows bad/grainy images at times but not always. A tech told him it needed new hard drives installed as they have many years of usage on them. I have found exact replacements of what is in it but need to know what is involved in replacing them to make it work. It is a SDVR-16-320, DUAL, SS2, NTSC/PAL. Any help is greatly appreciated.