Zenith Roundie Changes, Improvements, & Issues

[bhegges]

I am digging into two Zenith TVs I picked up. In searching old topics and studying the schematics I am curious what others have experienced, what was good, what should I look out for?

The first chassis is a 25MC33 which I believe was their 4th-ish generation color roundie chassis from about 1964 and the second is a 24MC32 which followed. I have read that vertical output transformer failure may be common and some of the plastic coil bobbins can disintegrate. The 24MC32 chassis does not have a horizontal linearity coil and also have different part numbers for the horizontal and vertical output transformers.

Zenith had just a few years selling color roundies before rectangular sets came out. Were the above noted changes along with other changes for cost savings or did each color roundie chassis provide some incremental improvements?