I ride 96 fxdl with 39mm showa forks. Last year I heard some noise coming from my front end.
Being an experienced rider I new the springs were bottoming out, so I ordered set of progressive susp
sprinngs,installed them ,took a test ride and the problem was still there. Now, I knew for sure that the problem was neck bearings. Week later I replaced old bearings,put new ones,test ride,the knocking noise is still there. Now I knew 100% that the problem was in internal fork parts,bushings etc.
Ordered new ones, installed them,all high quality made in Japan.Filled up forks with Screaming Eagle
fork oil, well another test ride and the knocking noise is still there. I figured out that that's normal,
this is the way those old forks work.
Few days ago I checked gas tank front mount,the screw was loose. I tightened it up,using some thread lock, afterwards NO MORE KNOCKING NOISE. What a beautiful ride now. Now I have brand new
front end,I think at least 10 years to go without any worries. Mat

 

Glad you found out the problem.It's just human nature to think the worst case.Allways check the easy things first.