Appreciate the "Ask Me".
I am assuming that you have more than just familiarity with electronic components and circuitry, the use of a DVM and a soldering iron. Further, that you have access to a service manual.
Width problem is basically insufficient horizontal deflection, then analysis would have to be in the horizontal section. Areas to initially focus on:
- 12V line and pin 29 of IC401;
- 110 V peak to peak at collector of Q403, if yes check Q 402 & 404 as well as T401;
- other components that affect the horizontal size are:
- Q 405, 406, 407 & 408;
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.
Good luck and kind regards. Thank you for using FixYa.