He says his Tech is 1964. So definitely a ZAMAK top cap and a brass or stainless steel bottom plate.I thought that Tech's were made of plated brass, not Zamac --
. . . I was wrong ?
Those Techs are pretty well made.
Now on the whole to ZAMAK or not to ZAMAK thing.
There are different grades of ZAMAK. I don't exactly remember the designation, but some are better than the others. The 60s-70s Techs are made of one of the better grades for sure. I remember reported cases of 22-23 years of daily shaving with a Tech before the plating starts peeling. Even then it was only a 1-2 mm spot and the razor was still usable.
It all depends on how you care about the razor, but also how often you unscrew the head (those threads are plated too, right?), what is the place you store it while not in use, and how often you use it. Let's not forget a razor needs cleaning.
With the ZAMAK razors made in the last 20-25 years some users have reported even 15 years of use before deterioration. But most of them didn't use the razor every day. I've had a DE89 screw snap in ~8 years and that's not even with everyday use (Yes, I was young and stupid, and tightened it as much as I could).