I belive Dave hit the nail on the head (David K3KY)
The Ft-757Gx uses a grain of wheat lamp fuse in the front
end and the lamp you are looking for is
located onthe main RF unit (FD1) F1001
The Yaesu Technical Supplement for the FT-757GX list the
Description as a BQ041-22803A what ever that is.
And part number Q1000010
I'm sure just about any little small bulb
will work in it's place restoring the signal path, however
you may be able to get exact replacement part
if you really want it. Call Yaesu Parts at 714--827-7600
Hope that is of some help to you.