MG Car Repair: 1952 TD generator, wont, jumper wire, ammeter

Question
With engine running, the ammeter shows a "pulsating" discharge. just twitches to discharge at idle, revving it up does not change. turn lights on discharges more. Ran it disconnected, with a voltmeter at the bigger terminal and ground and got around 4 volts. Jumped the big terminal and the little one and get nothing. A test procedure from another site says I should get voltage, that increases with rpm. Took it to a shop and the guy says it's okay.  

Answer
Hi Craig.  Disconnect both wires from the dynamo.  Connect the two dynamo terminals together.  Run the engine from tickover to no more than 1500 rpm.  You should get a voltage at the jumper wire that increases with speed.  If not, the dynamo is shot.  If the above test works OK, then your voltage regulator needs to be checked out, so get back to me for more instructions.