All 8 lights are lit on the mail unit. If the HD had failed, how hard would it be for me to install a new HD and get it working? Would I need proprietary software?

There is a 9 pin cable that looks like a serial cable. Can I access the HD through this to see if I can browse it?

I had thought that the Vodavi 5000 controller was the brains of the operation with shuttling calls to the attendant or extensions. What does this box full of circuit boards do? The installer left a glass tube-type fuse taped to the outside of the case suggesting that we might need it to replace a blown fuse at some time. I can't find a glass fuse anywhere inside without removing circuit boards and looking further.

Any more suggestions would be greatly appreciated!
Thanks
Greg