Welcome to the club!
Odds are you will probably have to scrounge for a transformer from another oscilloscope.
I'm working on a LBO-302 oscilloscope and the transformer in mine does not match the transformer in the schematics.
If you do find a parts machine, check or make sure that you ask the seller what the Secondary winding output voltages are written on the label to ensure that you're getting the correct one.
I'm guessing that the higher-rated fuse, allowed the fault within the scope, bring the transformer to an early demise. Which is probably obvious.
Good luck with your project!