The first Winchester push feed Model 70s (1964 to about 1968) were well designed, but the execution was pretty rough. You can tell them easily as they don't have a "G" prefix to the serial number. Gun writers at the time of the change over, especially Jack O'Conner, were aghast at what they considered the degradation of their favorite rifle; what is now refered to as the Pre-64 Winchester.
A good friend bought one of these post 63 and pre-G models in 1968. During a bear hunt in the Sangre de Christo Mountains in Colorado, the rear sight blade fell out and the extractor chipped off when unloading the rifle in camp. I noted two broken firing pins from Model 94s made in this time frame, so Winchester's quality control with metalurgy during this time frame extended to other models as well as the Model 70.
Around 1968 or so, Winchester realized that they had to improve the quality of the "Rifleman's Rifle" to stay competetive. That they did and the improved models have a "G" prefix to the serial number. These are well worth buyinga and using. It was also at this time that Winchester designed a great bolt guide for the push feed 70s and the later Classic Model 70s by cutting a groove into the lower locking lug that the right side rail rides in when extracting or chambering a round.
As noted in previous posts, the 80s and 90s brought about a nice change in quality at Winchester.