Although you said you sent the same cable you previously used, that seems unlikely unless you had most recently connected it to a PC instead of a Mac.
The problem is that it is not actually a SCSI printer. It sounds like you're trying to connect it using the parallel port, which is meant only for PCs but can easily be mistaken for SCSI. She needs a Mac serial cable (aka. a Mac printer or modem cable.) The Epson SC 740 has this port as well -- it's the one that is not USB and doesn't look like SCSI.
I hope the rest of this is not stuff you already know. Thought I'd include it just in case...
You need to use a cable with both ends looking like the one pictured here:
http://www.csun.edu/~lg48405/sed618/...cs/Image12.jpg
Note that it may also have an icon of a printer or a telephone instead of the two arrows, but they are physically the same and can be used interchangably.
Also note that the ADB (keyboard and mouse) cable can look very similar to a serial {edit: oops, originally write ADB again!} cable but they are not compatible, and are usually coiled rather like a telephone cable. This is
not the one you want.
A Google search revealed this page with a key to common Mac port icons. You might find it helpful:
http://www.betweenborders.com/io_icons/index.html