Herman Miller LCW ????  

I was lucky enough to pick up an Herman Miller LCW at a yard sale for only $2.00. It is ok shape some nicks on the legs a chip on the back veenner, etc.. It does have the oval shock mount and it has the 5-2-5 screw configuration on the bottom. No label but a handwritten number on the bottom 597130. I am wondering what year production this chair might be. Also have 2 early fiberglass armshell rope edge chars with the X base - found at a yard sale for $5.00 - but both have small stress cracks on the seat - is it repairable and how do I repair them? Thanks for any help. PS it helps living within 30 miles of the Herman Miller factory in Zeland Michigan. Lisa