Advantest R6142 diagnosing for no power up

[ShmoeMo]

G'day guys.

I recently got my hands on an Advantest R6142 Voltage/Current Generator.

It is rough and has come corrosion on resistors and legs but i have tried my best to clean it off and check the effected components to make sure there are no breaks in connections and they are still reading specified values and there are no shorts.
 
It however does not power up correctly. Sometimes when i power it up i get nothing but a click and sometimes i get a click and some random character or segment on the readout or mode light, some of the button lights come on and it just cycles through that flashing on and off until i power it off. Pressing buttons does nothing.

I have been through the troubleshooting steps (Stated in service manual for no power up) and gotten to the point of checking for high and low signals between TP2 (GND) and pins 30-37 of U1 (HD63B03) It specifically asks "Does the voltage change from high to low at pins 30 to 37 of U1 when the circuit between pin 1 and TP2 (GND) of U11 (TL7700) is jumpered and then it is opened" When running this test my idle voltage is around 3.3 -3.7 v on these pins (depending which pin I'm on) and when I close the connection between GND and pin 1 of U11 the voltages on all pins comes to 4.8v then back to 3.whatever but never sees a "Low" signal.  If the test results are incorrect it says to "Check, U1, U3, U4, U6 - U10, U33 - U35, U38 and U46". This is where I am stuck as I have no idea what I'm looking for on these mentioned chips.

I have attached the service manual below and the trouble shooting section I'm following is 6.3 - 6.6.

If anyone could help me out here it would be greatly appreciated.
If you would rather chat on discord to avoid spamming the reply's i do have that as well and am quite active on it. If we can reach a solution i will be sure to come back and update the post.