How do I get an Excellon Drill file with 2.4 precision and trailing zero suppression out of EAGLE?
Change Device to "EXCELLON_24".

Here are some lines from a .XLN using Device="EXCELLON_24":

...
T01C0.0130
...
T01
X13969Y11517


And here are those same lines in the wrong format using .XLN for Device="EXCELLON":

...
T01C0.01300    
...    
T01    
X139686Y115173


This wrong format causes the 10x NC Drill error shown above; I did not check this with GC_Prevue, but I saw this 10x problem when uploading to OSHPARK.