The C926 capacitor is one of the components associated with the vertical scan circuitry, however although in a large number of chassis this is a common failure point along with either bad joints on the vertical scan IC or indeed the scan IC having blown, the symptoms you describe do not match up with whats generally observed when any of these components go faulty, which could indicate the fault being in an entirely different location. Scan component problems can vary from the picture intermittently shrinking vertically, occasionally doubled up lines seen across the top of the screen, a single white horizontal line across the middle of the screen, then the set immediately going off leaving the timer light blinking.