I found some screws that I was not aware of, they were covered in gunk, once out I got good access to everything, I'm not sure what the Squealing sound was but once I opened everything up it stopped. That is the end of the good news though, once Dismantled for cleaning, it looks like some caps may have leaked and there is some quite bad PCB damage, looks like I've got some work on my hands repairing this one