Well, I would guess one of two things::
(1--the "wobbling pin has come loose from the wiggling gear"..
(Something I picked up from a late friend)..
Seriously..I know that chassis pretty well. It is like the CTC-203, BUT with more digital "stuff " on it.
The "squeal " is from the SMT transformer and is due to the fact that the B+ line is overloaded, because of a shorted Horizontal output. One of 2 things causes this (sometimes both.)
(1--bad connections on the coil from the driver transformer to the base of the h-out. You MUST resolder ALL of the paths from the driver transformer to the h-out, AFTER you put in a new one.
(2--a bad flyback. It MAY have been bad from the begining, OR it MAY have been "killed" due to the overload of current from the H-out short. How to tell?? Put in a new one, resolder the connections on the path to it (ALL of them!!) and see if it will "run". IF it "tries to start" but shuts down" Most likely then, the fly is bad.