I do not know what a 7.1 BAL is, but your description sounds like the moving shaft is bent or damaged at a spot. Can you move it up/down without a load on it to hear if it still does the same. I would look up the manual or online for lube or not.
2013 24RKSWE (27ft TT) Cougar 1/2 ton series
2013 Ford F350 4x4 CC 6.7 engine, 8 ft bed 3.55 rear end lariat package
Retired from Oregon State Police in 2011 than worked another 9.5 years as a small town traffic cop:
As of 05-2020, I am all done with 39 years total police work. No more uniforms for me.