Shifting in the "pulling cable" direction is rarely affected by anything cable related. So, my initial suspicion is gunk, keeping thebsmall engagement spring from catching. Flush with thin spray oil/solvent, shake out to dry, (outdoors, if you're married) repeat, dry, and hope for the best before doing anything else.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.