Can you please double check, I don't remember any mv40's old enough to have a 6. They were usually mv45/40, mv35, mv45/45 etc. Not ready can be a host of things, but I would bypass the overtravel switches first. Nothing works because not ready is basically estop on the old machines. There should also be er1 er2 and er3 lights on the panel. Those with a couple diagnostic bits should tell you more or less where to look. The maintenance manual has all that in it.