I wrote everything down (which I should have done in the 1st place  ) and was a bit confused .

In fact the row 1 wire for switches 41, 51 and 61 connects to J208/209 pin 1 on CPU board . As Daniel suggested, mostly likely a broken wire in the chain , but I have continuity from J209 pin 1 to the row 1 wire on switch 61 (and the 2 switches in between) .