Thanks everyone
I have the 1N5408's for the rebuild, the guy who looked at the amp gave them to me after he told me the original 1N1697's and the PT were blown.
I know to use the correct fuse
After all, I don't want to take out the PT again.
I'm happy to hear the 1N5408's are more robust since the apparant original problem was the diodes going.
Got something to do for the rainy weekend now.
Trivia---do you know the Magnatone M series amps have a OT safety switch?
The PT and rectifier circuit are on a separate chassis mounted in the bottom of the cab with the rest of the circuit up top.
There is a red button on the chassis that gets depressed when installed in the cabinet.
When you take the chassis out of the cab, the button opens and opens the circuit to the OT and cut power to the exposed circuitry.
Interesting