BMW Repair: Speedometer, wireing harness, mechanical skills

Question
My question is for a 1984 735i with 242,000 miles on it, still runs good!  The speedo just stopped working.  No noise, no needle jumping around.  Is it cable fed or electronic?  Can a person with average mechanical skills fix it?  Can you recommend any parts to start with?

Answer
I believe it's electric.  first check the connection from a sensor on the bellhouseing to the wireing harness in the engine bay, if it's wet or corroded the sensor will not work.  pull off the sensor from the bellhouseing and clean/inspect it, if all seems well, the next step is to check the connectors to the speedo cluster  and test it with a known good unit,  the problem may be contained in the cluster.
-cheers

Yer cars just a BABY  My 325e has 350,000 original eng/trans