I think a lot of the issues lie with the Tape masters. People really didn’t give a damn about good TV masters back then. I think a lot of these issues were almost invisible on even the best CRT monitors.

And an update on what i call the Klasky Cuspo effect. Looks like i was wrong, i’ve seen it all the way out to Season 5, after KC stopped producing animation. Its likely that the jagged frames are from principal animation, whereas the clean frames could be pickups, animation done by different facilities or though a different telecine workflow. The fact that it is present in some scenes and not others and sometimes not present in shots that could very plausibly be pickups or retakes.

That being said theres a special feature on the season 2 DVD where a simpsons producer in america has a 35mm version of a scene on a Flatbed editor, suggesting that Telecine is done in america rather than Korea.