its an old machine and low to medium range quality, so repairs would be more expensive than its worth , thats if its faulty, if the transformer is gone ,definitely too costly to repair, i cant say for sure looking at the pics ,but it does nt look like it has been "cooked" ,its just old, as said-- just give it a gentle clean up ---un plugged of
course and then a low setting with a small 2.5mm rod to try out. Theres a thermal cut out on these to prevent overload ,so if that has failed thats when or how they overheat from over extended use at high settings. Some have a fan for
cooling the trans down that is too small or jammed up /damaged . The pic of the front of the machine shows an approximate guideline of settings and the arc welding rod size diameter 2.5 to 4 mm to match them , the metal printed on plate is showing its rated output and use time at settings, its 45 amps draw at its max of 200 amps .These old tech welders are at the limits of most older electric boards and the 13 amp fused plugs , they also lose efficiency as they age , so okay for small jobs and repairs, but bloody annoying for when you want to make something like a trailer as it will slow you down and keep tripping the rcb or worse ----the main fuse. When new it had a 30% use at 200 amps ---flat out --max setting , so 3 mins of use and then 10 mins of cool down ---if the thermo cut out was working.