vestel 11ak30 (watson tv) vertical problem
 

This set is at most 2 years old. Original problem was vertical
collapsed, (no burned resistors etc or other visible problems). I
replaced the vertical IC601 (tda8174aw). That brought back the picture,
(seemed alright for about a minute) but there is horizontal tearing and
loss of lock - scrolling vertically, and also even horizontally
unstable. The OSD is visible. Besides which, the vertical IC gets very
hot in use. I turned the set off as soon as I realised (2-3 mins
later).

Thinking this might be due to a poorly rectified 26v supply to the IC,
I changed caps c631, c603 and c633 but no difference (I had also
previously, when replacing the IC, changed diode d610 as a precaution
on the 26v line). I have checked the soldering, the heatsink
compound... any suggestions on where to look now? What might be the
reason for the IC overheating? defective yoke? I suspect this goes hand
in hand with the picture instability....
thanks for any sugegstions,
Ben.