If you can, I suggest you pull one breaker and bring it in to a real electrical supply house, they are your best bet to get a workable replacement. Do not go to a big box store, they are probably not going to know what you need.
There are lots of places that sell old/obsolete breakers. Take pictures of on of your breakers. Top, side and bottom. If there is still a name plate on the panel take a pic of that too. Go online and search obsolete Sylvania breakers. Email them your pics.You are right. The big box stores don't have them and the one real electrical supply place was no help either. I live in riverside ca. Do you know of any local shops. The two breakers that need replaced run most of my house so I can't leave them out for long
What makes you think you need to replace individual breakers?Well, different people have given me different names for it. Is it because the names interchangeable? Honestly I am in sticker shock at how expensive the damn things are. I'm going to have to replace it soon. I don't want to be sitting in the dark, kicking myself for not taking care of it sooner
I wouldn't suggest trying to learn on the main breaker of a zinsco box.I haven't changed one before but it looks simple enough.