"filament in the salt shaker" is the interior glow plug(in passengecompartment)
that allows the operator to see the plugs in the engine work.You may
be right about It's affect on the system[if it's out no glow]


I can't remember what or where it is on the 240D , but M. B. loves to
use an aluminum strip type fuse for the glow systems (1/2 inch wide
by 2.5 to 3 inches long) LOOK closely at it ;a micro crack will affect
the glow rate.(better still use a multimeter to check the continuity
and resistance of the fuse)It will be in it's own black box in the
engine compartment...follow the hot lead of your glow system.