I have owned a M59 1st generation since ~ 1980 and love it.
Fired thousands of rounds through it and is very reliable, polished the feed ramp when I bought it (used) and a couple years ago replaced the guide rod spring.
Last year I let a friend play with it on the range & he dropped it, since then the 'lollipop' rear sight is sloppy & would like to replace it. If any of you can lead me to one I sure would appreciate that.

Enjoy those M59's!
Steve
[email protected]

UPDATE>
Found a replacement rear site at Jack First (605)343-9544 in South Dakota - referred by tech dept at Brownell's.
Becky there at Jack First said it would go out in the mail today (4-26-12)
Keep your powder dry.
Steve