I've got an '82 Matsuura MC-500 in my garage. I've got it wired up with an RS232 cable (actual serial port on my PC). I will often find that it is missing end of blocks, or even dropping a J0. I read that running it too close to wiring, or fluorescent lights can cause this, so I rerouted the wire as best as I could. Still does it. Also, on long files, it will just drop the last half of it, it seems.

Baud rate was originally set to 1200. It did it then. So, I jumped it up to 2400, still did it.......