If you "lost" a couple pads, you do nothing too special, either bend the part leg towards the remaining track and solder it there (you may have to scratch the anti soldering paint to leave copper visible) or you make a small wire loop which you solder to the remaining track , the end ring becomes the new "pad".
if you destroyed more than 5 or 6, the bpard can be considered "lost" because even repairing all, it will be too weak and easy to crack again , simply by vibration.
To avoid losing the amp, maybe you can buy a power amp kit and mount it there, using the original power transformer, plus the preamp , cqbinet and chassis, of course.
If the original PCB is too damaged, it may be the best option.
What amp is it?
Post a couple gut pictures.