Contents of Errors running

Errors running ${\mf METAFONT}$

The task obey file lj-fonts sets up a wimpslot of 960k which is enough for ${\mf METAFONT}$ so you shouldn't be getting an error about the wimpslot being too small. One error you might run across is ${\mf METAFONT}$ complaining that it can't write the .tfm file for the font just created. This can be the case when the .tfm file already present

is locked or
was created with a different mode / resolution.

In both cases the best option IMHO is to delete the old .tfm file. Again, I feel someone sharpening the spike...