Perhaps this is a "newbie" question:

Today after a long computation (I let it run overnight) I
obtained a particular sought-after subgroup of a general linear
group over a finite field, say GL(3,7). I needed to study
properties of the center of this group G, and carfully defined
Z := Centre(G). Much to my surprise everything broke down, since
Z is evidently an "internal" function used in conjunction with
finite fields.

After making such a blunder, is there any way to recover
the original definition of the internal function Z?

Thanks,

--Walter