If you have technical info as to which pin on the transformer is which then you can meter the windings to see if one of them is open, but I'm guessing from what you've written so far that you dont have access to such information.
The only way to be sure that the trans is ok is to unwind it, that is a tricky task for a noob, you'd need to mic the wire size of every winding and take not of how the wire is laid and what insualtion material is used and how its positioned, in fact for a medical device I suggest that you leave well alone, if you think its the trans then get or salvage at worst another one.
I've had a couple of pc supplys where the chopper trans has gone dead short and taken out the transformer primary, so its quite possible that is the case.
The only way to be sure that the trans is ok is to unwind it, that is a tricky task for a noob, you'd need to mic the wire size of every winding and take not of how the wire is laid and what insualtion material is used and how its positioned, in fact for a medical device I suggest that you leave well alone, if you think its the trans then get or salvage at worst another one.
I've had a couple of pc supplys where the chopper trans has gone dead short and taken out the transformer primary, so its quite possible that is the case.