Fix an winding arching transformer

[gkmaia]

I am fixing a vintage tektronix oscilloscope that was blowing fuses.

Wen to inspect the transformer with a HV insulation tester. Some of the windings are arching and I will need to re-wind it.

I've winded transformers before and got the tools for that but never put one a part with the intention of preserving some of the windings.

Need some ideas on how to melt the wax/rosin to release the iron plates without damaging the enamel of the original windings in case I can preserve any.

By looking at some datasheets I come across values like

Temperatue index
Heat shock
Cut-through

Which one of these values relate to the maximum temperature the enamel resists before getting melted?