A few years back I did a successful rewind of the HV transformer in my 7934. It is still working to this day. Now I don't really want go get into the transformer rewind business, but I will share a potential resource that might be able to help. I'll warn you up front, it won't be cheap.
The company I found that might be willing to do a rewind for you is Sun Transformer, A division of STC, Inc. Their phone number is 618-643-2555.
The contact I had was a gentleman by the name of Les Vaughn. The time frame was from April of 2014.
Just a quick note here, there have been several other folks on this list that have successfully rewound the 7934/7834 HV transformer. It is not
easy but can be done if, and only if the bobbin and core are still in good shape.
Karin Anne Johnson K3UU
Palm Harbor, FL