BTW, the capacitor doesnt have to be electrolytic. it can be a bad/leaky/shorted ceramic or mylar cap.
Check: TDA1170 vertical deflection output IC, There is a resistor/capacitor filter between Pins 1 and 12. This sets the vertical linearity, If the two 0.1UF capacitors are bad/leaky, or the two 68K resistors have drifted or opened, or the 470K. You will have this issue.
the 68K resistor between 1 and 12 sets the linearity, However its in series with an 0.1UF cap, and i would suspect this first, as if it goes bad the 68K resistor wont have much effect as the overall impedance changes.
Check: TDA1170 vertical deflection output IC, There is a resistor/capacitor filter between Pins 1 and 12. This sets the vertical linearity, If the two 0.1UF capacitors are bad/leaky, or the two 68K resistors have drifted or opened, or the 470K. You will have this issue.
the 68K resistor between 1 and 12 sets the linearity, However its in series with an 0.1UF cap, and i would suspect this first, as if it goes bad the 68K resistor wont have much effect as the overall impedance changes.