Rob,
Does it have a hard drive now? If you have a hard drive your drive is getting full or is full. If you connect via rs232, you should be able to transfer the file to the hard drive then DNC from the hard drive using the machine's DNC option key, just select the file.
Have you tried RS232 to your laptop?
I think if I did anything I would add a network card to the machine.
That should be an ISA network card. There's info here on the forum where others have done the same thing. Milltronics will email you the setup info, all you have to do is request it. You can then DNC over the network connecton.
All you'll need is a crossover cable to connect to the laptop.
The other upgrade is memory. The motherboard should max out at 4 megs.
You may have to attach a keyboard and access the CMOS to update it for the memory install. Or it may be automatic depending upon the motherboard.
I have a newer MB19 with 4 meg RAM, hard drive, and network. I haven't had to use DNC yet, I split the big programs up if I can. I don't use the hard drive much either, I use a folder on my PC for storing the files.
pix
Some of my best finds were in the trash....