Yes it is easy to lubricate. Pull the instrument cluster, unscrew the cable from the speedo, pull out the inner cable paying attention to which end goes to the cluster and clean the hardened grease off to it. Spray it with Würth HHS-K which is a great grease that is in a light carrier. After reinstalling the cable, spray plenty down the cable and you’ll be golden.

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2014 GL450 76K - Wife's DD
2013 GL350 123K - My DD
2002 ML320 300K hard miles (workhorse)
2001 Z3 105K the 4 weeks a year ride
1995 E300D 189K - Rarer ALL options one ortho seats & all

Past ones
2015 XC70
2008 V70
2003 XC90 2.9 (POS)
1998 Wrangler (sporting a SBC 388)
1995 E300D 500K - Should have kept it!
1985 E300DT
1984 E300DT-T
1984 240D Gray market