I have a 98 XJ, had this problem for years. I could push the cluster in by hand and it would come alive again. BUT.... I have now fixed it! you have to take the dash apart and pull the cluster out, you'll see the 2 green connections ( very loose ) I taped some shims just behind the clips to stabilize it and bring it out just a bit. ( i wish I had taken pics!!!)
it's a poor design, even with the cluster in the connections were always free to move at the back.
it's been 2 weeks and a lot of bumpy roads and so far so good!
hope this helped.