Helpl with Output transformer replacement

I believe I have located the problem in the Pilot sa 232 amp I am trying to restore. It appears that there is a short in th primary of one of the output transformers.

1. First, I was wondering if anyone has ever tried to rebuild these things - is it possible. Comparing the resistance across the primary leads of the two transformers and they appear to be the same. The problem is that there is a leak to ground. I'm thinking that the wire must be touching the core at some point. It would mean removing the metal if this is possible. How is the metal held together? Is it possible to take them apart? Another idea is to insulate the transformer from the chassis to prevent the short to ground. Does this idea have any merit?

2. If repair is not possible, what are the replacement considerations? I have looked at the Hammond transformers which look similar to mine but the impedance is not the same. Can this be compensated for by using a resistor or does it even have to be exactly matching? I've done some searching and there doesn't seem to be much available unless you go to custom winding which I imagine would be quite expensive.

Any thoughts would be appreciated.
Norman