In the early 1980s, I remember seeing a western-style cartoon that featured a scientist who had created a kind of gas that damaged robot's machinery. I can't recall whether the scientist was evil or not. However, the bad guys (whoever they were) got wind of this invention, and there was a race between to recover the gas cylinder from where the scientist had hidden it. A robot with the good guys' mission to retrieve it was accidentally exposed to the gas and damaged, and in the confusion, the bad guys got away with the cylinder.
The villains then modified the gas, so that instead of just damaging robots, it "mutated" them and turned them evil. Then they released the gas in domed city, and all the worker robots started attacking the population. They people were evacuated and the dome sealed, but I remember the good guys watching video footage of overgrown construction robots trying to break out of the dome.
That's all I remember. Does anybody know what this show was?