My 64 vibroverb has the transformer your looking for. It’s a great sounding amp and has been since 1970 when I first got it. I have no idea where to find a replacement tranny but would probably just buy a mercury magnetic one that they supposedly blue print. It is smaller than the bandmaster and 40 watts is really max out of it and plenty loud. I have a d130 JBL that has that surf guitar sound in buckets. I love the sound with a pair of H30 celestion in a 2x12 ext cabinet.