HP Laserjet 4050n sometimes prints fine, sometimes prints gibberish. Help?

It is an old printer. I'm using it with a Windows 10 machine. There is no USB port on it, so I've got a USB to parallel port cable hooked up to it. When firing up the computer with the printer active, it is automatically found and installs the PCL 5 driver for it. And like I said, sometimes it prints... show more It is an old printer. I'm using it with a Windows 10 machine. There is no USB port on it, so I've got a USB to parallel port cable hooked up to it. When firing up the computer with the printer active, it is automatically found and installs the PCL 5 driver for it.

And like I said, sometimes it prints perfectly, sometimes gibberish. Sometimes it will print fine in sections, and big black random shapes in others.

Suggestions on how to fix?
4 answers 4