The parallel ports are the problem. Newer computers are not using them. Also you have to be sure yours is a 32 pin not 64.
I have a guy in SW FL that just set me up with a used Dell with 2 parallel ports. The computer works great, 90 day warranty and he is there for support. (he has lots of them)
I paid $300 that included a flat screen monitor, 2 ports, mouse and up dated Video card.
Let me know if you need his name.