The schematics online are shit but I believe you can adjust POT1 to tweak your 5v. Go slow with the adjustment I think its right under the big heatsink. Anyone else confirm? edit: i think its blue

Trust me the least hacking up on the board you can do the better. Also if you can't determine the 5v cap as of now you run the risk of making the problem worse and ruining your whole 5v section. Do you have hakko desoldering gun?

To answer your original question... C3 and the BR beside it could be the culprit, but again would need someone to confirm as the schematic is shit. If you had the board out you would be able to more easily trace which capacitor is on the 5v line.

ok found it... mustang LE

Capture (resized).PNG

Cool, glad to hear it and sorry I just wanted to keep you on the safe side in case you didn’t know what you’re doing but it sounds like you do. Sound good and best of luck and yea my next suggestion would be to reduce the load on the 5v