My Emcomat 7 lathe was suffering severe backlash problems in the crosslide. Taking it appart I found the crosslide nut had given up, the anti-backlash adjustment had gone too far and the threads were worn. I was not able to find a replacement so I took measurements of the old nut and machined a new one in brass:
It seems I did not make any major mistake and the nut fits and works perfectly under the crosslide. No more backlash !!