Did you pull the fuses OUT of their clips to measure them?
Measuring them "still in the machine" will give you false readings of an 'OK fuse', because you're actually still measuring transformer windings, which make a 'blown' fuse still measure as a 'short' (fuse OK, false reading)......(this catches everyone out).

You'll need to lift just one-end of each fuse out of it's clip, then re-measure the fuse-ends....within seconds you should find a blown fuse. (assuming the fault is a blown fuse, and not something deeper in the system).
Perhaps also try unplugging/re-plugging the connectors on your boards in the backbox, probably one connection is intermittent that is causing your fault.....TRy to locate the connectors that carry the transformer wiring onto the power-supply board etc....these go intermittent a lot.

You might even notice the machine come to life by merely jiggling the wires slightly on each connector.

Is Led104 labelled what it does??
Do u have the manual handy (or a download), to see if Led104 is a supply rail like +5volts or +12volts etc etc??

Sorry, i don't know MM at all (inside), but checking the above 2 suggestions will probably solvew your prob in time for the BBQ. ;-)

Hope it helps.
MM.