Look at this horrible “repair” job someone did to the power supply of this Yamaha DX21 (which broke again of course)
The main electrolytic capacitor has been replaced with just some other one, definitely not a low-ESR type, connected with quite long and thin leads and then glued into place somewhere in the case. The switching transistor is glued into place too and the traces leading to it are almost, but just not quite broken.
An additional power LED had been added, but instead of connecting it to the 5V rail, it is connected directly to 230V via an capacitive “led power supply”.
Last but not least there is some strange sticky stuff all over the place, might be electrolyte from the capacitor, or some kind of glue that was used for something. It is hard to tell, it is an awful mess in there.
In cases like this instead of trying to fix the existing power supply it is better and cheaper to replace it with a new one.