Thanks for pointing out the truncated URL above, fixed now. I'll make a note in that section which way the diode should be, it's clearly not obvious to everyone.
The design would have been far better with a self resettable fuse or something, but was either removed to save money or was simply an oversight. If you wanted to, it would be tidy enough to lift one end of the diode and solder an axial fuse in series with it. A series resistor won't be ideal as you won't be able to supply the required current and maintain the output voltage, i.e. you'll have issues with voltage drop across it.
4.3V at the terminator won't be an issue for active terminators which regulate this to 3.3V anyway. Even passive terminators which use a simple 220/330 Ohm resistor divider to derive 3V on tri-stated lines will only suffer a 14% error (2.58V as opposed to 3V) which is still well within spec. Actually I just noticed in
this Wikipedia article that the termination power is generally at 4.3V anyway. Seems Commodore's design wasn't all bad.
