Xof - Woodworking

Hello all, Lately, I got a hard time cranking up the blade block. I has happened in the past, and the solution it to clean the rods and add some dry lube... this has worked in the past very well. This time though, the crank is going very smoothly, but the blade does not go up. I looked into in and it seems that the vertical threaded shaft now has a little play which is the source of the problem. Anyone knows how to reduce the play of this vertical threaded rod? Thanks a lot!