Transformers very rarely give trouble - so rarely to almost dismiss that thought.

Your problem is far more likely to me fuse/ fuse clip/ power supply/ connector related.

Grab the circuit diagram and start measuring voltages and work your way through (or BACK) and make sure ALL the voltages are correct.

You can't guess this and you can't tell by looking - measure, that's what meters are made for!!!

I have heard the large transformer is almost bullet proof whereas the smaller transformer can have issues?????????