All the amps are fairly similar. You probably need the service manual because it gives the details of the circuits. A few individuals have fixed theirs without a service manual. You need a volt/ohm meter and a soldering gun (along with the device that allows you to suck up the melted solder).
The main electrolytic capacitor is the first thing to look at. They deteriorate with heat and age. Also any blackened device should be replaced along with the devices on each side of it (if they test poorly).
That stated, I decided to get a PE 500w BASH amp and just replace the existing amp that I had on a 15" subwoofer. A difficulty is getting plate amps that are almost the same size as the the existing plate amp.
The PE BASH amps are on sale until December 31.
Addendum: Quick repair. I told my son to glue 2"x4"s in a rectangular shape to the back of the subwoofer. After lengthening the wires that went from the amp to the driver, he merely screwed the amp to the 2"x4"s.