Thanks Diver, that was very helpful. Once I searched using your suggestions I came up with a number of alternatives and am happy that I have the right replacement.
Now I just have to find the other. It's odd that the first diode has PJ6156 and GS1J ... and I had searched using variations of both numbers and found nothing until today.
The other diode may well come from the same manufacturer, with its PJ612K and QE ... but I'm still at a loss with it.
I did have some success with another TVS diode that had the marking 'BUG'. Turned out to be a SMBJ15A-TR, though I spent a lot of time with all its other numbers ... I really didn't expect BUG to be the legit marking!