Speedo quirk

[tasattack]

This is a very miner issue, i have a 1980 olds delta88. what i think is a cable attached to the speedometer needle squeeks and from a stop to a normal acceleration the needle bobs.

My question is this: is there anyone familiar with this car enough to know if there happens to be a greese zerk or a way to access the cable to greese it or even replace it if needed. it sounds more like an interior noise, meaning it sounds to me as if it were comming from behind the dashboard.