12 miles from home today, my rear derailleur decided it only wanted to be in the two lowest gears.

Once I got home and took a look at it, it appears the cable is hanging up either in the top housing along the handlebars and frame, or in the brifter itself. It seems to be moving freely everywhere else.

I'd recently put on a stem with a steeper angle, and I wasn't completely in love with it, so I went back to the shallower one I had on, in case the housing was marginally too short. (It was shifting fine right after I put the stem on, fwiw.) After doing that, lubing the cable at the housing near the derailleur and under the bottom bracket, and just generally yanking on it here and there, it's shifting some, but not very well, and it's really reluctant to go into the highest gear.

I seem to recall someone saying that the cables should NOT be lubed at the brifter because of the risk of light lube/solvent getting into the grease in the brifter. Is this correct?

Is this just a sign that the cable needs to be replaced? They're almost two years old but there's no visible sign of wear; I don't want to bother if it isn't going to help. What about replacing the housings (grrr... PITA... )

Any other thoughts?