If the further notches in the rod won't engage the ratchet, it sounds as if the notches in the rod are worn. You could either replace the notched rod, or refurbish the notches with careful application of a file or angle grinder. Take a look at the ratchet pawl as well - it is just a piece of spring steel sheet, and sometimes loses its tension or gets bent by harsh handling. This is a fairly common thing to find on well-used Greenfields, and is not difficult to put right.
