It would take a lotta current to burn that resistor. Good chance one or both of the output transistors are fried. I doubt the output transformer could take that much current either, but ya never know... Try measuring the resistance from -9V (meter negative lead) to either side of the output transformer primary (meter positive lead). If that's good, then we can move onto testing the transistors. If the transformer is fried, all is not lost, I'm sure we can find a usable replacement. How far are you willing to go with restoring this amp?
Here's the background story of that amp and my involvement.
Howard Chat owned a company called Cases Inc. They built shipping containers that were used to ship amps, speakers, instruments, etc. by touring bands, in addition to more mundane uses. Howard ended up buying the Pignose company. The electronics inside the original Pignose amps were from an intercom.* Some smart guy figured out that they sounded great as mini guitar amps. Howard was having the amps manufactured in Taiwan. One day, his supplier told him that they could no longer obtain the germanium transistors. The provided an alternate amplifier design that used an IC power amp and a few R's & C's. Needless to say, it lacked the tonal character of the old design and basically sounded like shit. A friend of mine who worked at Cases Inc. contacted me and asked me to go see if I could help Howard out. I was into tube amps at the time so I realized right away that most of the tonal qualities resided in those tiny transformers. I told Howard, "you gotta keep those transformers." I replaced all four germanium transistors with silicon, using some hefty 2N6124s for the output. I also replaced the thermistor with a 1N4148 and tweaked the bias resistors. Problem solved. I got something like $50, two amps and a Pignose windbreaker for a few hours of work. Howard told me, "don't replace the transistors in those amps, they work just fine as-is." And so they do.
* I have a story about making a mini-Champ from an old tube intercom I bought at a garage sale, that's a story for another day.