The zenith is off on the sync head which is why it has that trapezoidal wear pattern...reproduce head looks alright. The machine has had some mild sticky shed tape run on it at some point which is what’s responsible for the deposits across the entire tape path including the heads. I don’t see any severe wear on the heads, open gaps, etc. clean it up really good and try to calibrate. My hunch is it will still perform to spec. The sync head will meet a relatively early death with the zenith being off like that, but heads for that machine are likely not terribly expensive when the time comes. I wouldn’t jump to anything major...just clean it up and see how it does...my 2 pence.