Oxford mig 180 no welding as should

[Jonny weld]

Got an old oxford 180A mig welder transformer, guess early 1990.

on higher setting seems like to struggle to melt down and splatter as not enough power to weld.

Not sure if I have explained well but any idea how what could be?

 

[Shedendman]

Photo of the front?
I had one from around that time,transformer started going from the highest setting down
Bloody wicked on thin stuff though

 

[Tom O]

Could the capacitors be weakening I had one go bad on my Miller and replaced all 6 for a couple of hundred dollars when the smoke was released.

 

[eddie49]

There may a loose, burnt, or corroded connection somewhere in the high-current low-voltage welding circuit. A bad joint heats up and the resistance increases, dropping voltage across it and leaving insufficient power at the weld point.
Switch off and unplug the machine, remove the covers and check all the heavy joints on the secondary side. Even if bolted connections look OK, they may be corroded or fractured inside - especially if the coils are wound with aluminium wire - so open and re-tighten any suspect joints. Check the thick secondary wires from the transformer to the rectifier, and from there via the inductor to the MIG torch socket, and at both ends of the work return cable and clamp.

In addition, measure the voltage available between the torch tip and the work clamp at all settings of the rotary voltage selector switch. It should start at about 15 volts DC and rise to about 28v, in roughly equal steps.