Welcome to SCSI VooDoo neokm!
I can remeber the many, many, hours working out the "kinks" in my SCSI chains at home and at work!
First, if the reccommended settings don't work, try switching the adresses first, then physical placement on the "chain".
Note that a SCSI cable that has worked before, may not work in a new configuration as some cables have more "resistence" which can cause a false termination. If possible beg or borrow some other cables to see if that helps, or try switching to which devices the cables plug into.
Speaking of which, try NOT using any "built-in" terminator on your device and use a manual termination "plug". Sometimes the "built-in" terminators don't work.
As for your 25 to 25 pin connector cable, you could use a SCSI ZIP drive cable. You could probably get them quite cheap at a used computer store or ebay. BUT those were low-cost items, so you might just be buying trouble. Luckily SCSI cables are the same for Macs and PCs, so you should be able to find some bargains. (just make sure it is a SCSI and not a parallel cable)
Good Luck!