Rory's report has revealed a bug in GEN41.  The last significant line
of the code is "*fp = pp[j-1]" which in the example rites off the end of
fp.  It is OK in the manual example.  I am not sure why yet, but this is
old Gabriel code and I have not decoded it  yet.  Anyone have any ideas/

I have tried removing the address arithmetic for indexing to simplify
but no fix.