200 amp airco welder generator

[kidd4x4]

i just bought a 200 amp Airco welder with a 4 cylinder contintal engine the machine seems to be complete minus the magneto, The voltage switch works on the first three settings the next three are burnt out, so being a novice i have many questions like where might i find a switch. Looking at it i think i might be able to repair it with some thick coper plates but a good one will make life easier. is that normal to burn out with time, how dose the vac from the motor witch goes into the copper coil effect it, i understand the vac to the diafram. any ideas on locating a magneto for reasonable price. and finally some feedback on the machines reputation will help as to how far i go with fixing it. why is it said to be 200 amp hornet yet the dial goes to 300 amp thanks any feedback opreceated