On my plus I had to resolder the Flyback, Yolk Connector and the analogue -> logicboard connector (J1), I believe the flyback and J1 where the issues but the Yolk connector was visibly cracked too. You also need to make sure you remove as much of the old solder as possible and flow new solder on or you won't get a good connection
I'm betting it's the flyback joints on your board, they seems to often get overlooked when people are working on these analogue boards
The Dead Mac Scrolls, which is available out there on the 'tubes as a PDF, shows pictures of common faults and their repairs for the Plus and SE. It's a great resource.
Hi cheesestraws, Thank you for having interest!
I recently noticed that the LC575 and CC have slightly different capacitors, resistors, and rectification.
Since I am only posting what I tried, I would like to try if there is a difference in interpretation...