Lines 7-11 of PROCcalc_sign  (lines 814-818 of !RunImage) are:

  IF INSTR(Entry$,"-")=0 THEN
   Entry$="-"+Entry$
  ELSE
   Entry$=RIGHT$(Entry$,LEN(Entry$)-1)
  ENDIF

This needs to change to:

  IF INSTR(Entry$,"-")=1 THEN
   Entry$=RIGHT$(Entry$,LEN(Entry$)-1)
  ELSE
   Entry$="-"+Entry$
  ENDIF