BP said:
Basically, its not neat mathematically and fundamentally the issue is really the limited range and precision of using 2d6.
When Murphy strikes, there is an explanation for the result - at least in
hindsight: The pilot did not sleep well, he caught a cold, he was thinking
of the girl at the starport bar while going through the check list, there is
a minor problem with module 783-XD of the grav drive ...
Whatever it is, it can be turned into a modificator, preferably one the pi-
lot is not aware of (because otherwise Murphy would normally stay away)
- he can try to figure out what went wrong, and why, after the event, al-
though just as in real life he may never find a convincing answer.
In other words: I think 2d6 is doing fine when it comes to Murphy's visits,
the referee only has to open the door for him with a modificator now and
then, preferably at a good point in the plotline and with a little foreshado-
wing (NPC to Pilot: "Man, you look pretty tired today, must have been a
long evening at the crew lounge.").