Ed Kraushar
CVRS Member

These are ballasts, not grid leaks. They are in series in the filament circuit of the tubes and are usually of low resistance. Their purpose is to regulate the voltage going to the tube filaments. If a megohm resistor is used to replace them the tubes will not get any voltage. I have jumped them with low value resistors when open.
Radio Museum shows them in a partial schematic of the Aladdin Big Four.