With PS403 you mean the silkscreen that this component has on the board, it is a variable resistance; the problem is that I have no scheme of that device to see its value, to see if someone has it, anyway look at which components are associated with that variable resistance for example of such leg there is a capacitor of so many microfarads, of the other one resistance of so many ohms, etc. and maybe with a little luck I can tell you its value, its value should be in the order of approximately 1-150K, another solution would be to put a 150k closed butt and with the device on going up very slowly to Turn down the resistance value and leave it at the value where the device starts working well.