My 2001 XJ Wiper spline movies up and down on both side but more so on the drivers side, maybe 1/8". When I'm running the wipers it'll click/pop and it's obnoxious. There's no nut to tighten on the arm and the spring on both arms feels extremely stiff so pressure shouldn't be an issue. Is there a solution to this?

Thanks!
Bob

 

Good possibility the wiper motor bolts have loosened up or the plastic bushings are worn.

Remove the cowl panel and have a look.