Replacing Old LEDs

[Bradley Slavik]

Dear Classic Computers,

I regret that my EE knowledge was never deep and is
a little rusty now. I am refurbishing some old PC
boards and wanted to replace a few of the LED which
had become damaged or broken off. Here is my lame
question, how do I correctly pick replacement LEDs?
I know colors, and size, but how do I make certain
that I have picked correct wattage, etc.?

If some one with more experience could provide a
few sentences of guidance I would be grateful. I
can even put a Tektronix scope on it and take
measurements if necessary.

Bradley Slavik