[old_tv_nut]

Diodes themselves cannot cause jailbars. Jailbars could be gnerated in a circuit that happens to contain the diodes, but changing the diodes would not fix them.

Are you asking about replacing the caps or the diodes?

1.5 kV diodes can be used in place of 1.4 kV diodes.

1.5 kV caps should not be used in place of 2 kV caps. The rating may or may not be important for steady state operation, plus, it could be specified to tolerate temporary overvoltage due to CRT arcs or some other condition.