Bulkhead connector pins loose

[Andy_]

Apologies if this has been asked before, I couldnt find much about it.
Ive got an issue where the ballast resistor wire from the aux relay is dropping just over a volt.
Ive checked the circuit, I'm pretty sure its the bulkhead connector.

How do you clean up your bulkhead terminals ???

Ive been using a wire brush and terminal cleaner, theyre better but not 100%.

Either the male pins need widening, or the female ones need squeezing a bit. Dont know which to do.

Is there a tool for slightly widening the circular pins in the bulkhead connectors ?

[Bitsyncmaster]

The male round pins don't change diameter. You would need to squeeze the female pins tighter.

Note: The small wire in our cars is around 19 AWG so it can drop a lot of voltage is current is above 5 amps.

[Andy_]

I cant get the coil + voltage any higher than 4.8v

I have cleaned the aux relay terminals, bulkhead connector(yellow), ballast and coil terminals.

Ballast resistor tests 0.5 ohm each.
Coil is new. With an analogue voltmeter:
Battery jump post 12.4v
Resistor feed 11.6v
Left: 8.4v
Bottom: 5v
Coil: 4.8v

This is obviously very low. I get a great spark if i add a jumper from battery post to + coil.
All above tested using the same ground (engine block). Ballast earth to engine block grounded.
Any ideas at all would be gratefully appreciated

[Andy_]

Forgot to add, the above readings were taken with the ballast relay removed, so blue/yellow from starter to left of ballast, white top right, white yellow bottom right. Thought the relay might be the problem

[Bitsyncmaster]

The stock coil is 0.4 ohms primary resistance. Using ohms law, the 11.6 volts feeding the two 0.5 ohm resistors your driving 1.4 ohms so your current is 8.3 amps. Now to get the voltage over the coil, 8.3 times 0.4 = 3.31 volts.

Normal recommended coil current is around 6 amps so you have more then that. Don't worry about voltage, it's current you want.