Squeeling and Jumping speedometer

Unhook both ends and pull the center cable. Wipe of the slime. Spray in some cleaner that will remove the oil and sticky goo that is in the housing letting gravity move it through the entire length. Go to a local locksmith and get some Lock-ese Graphited Lock Fluid. Most of the liquid carrier evaporates and leaves the graphite to lube the cable housing. Stick the cable back in and reassemble.
I used to always keep a bottle of Lock-ese in the body shop for pesky speedometers back in the day. It actually works well on the door locks too, just don't over apply or you will withdraw black keys, leading to black hands and black pockets!