Restoring Linoleum?I have an old linoleum floor that is definitely showing its age (yellowing with age, dull luster). Does anyone have ideas on how to restore it to at least a shadow of its former self? It seems as though a deep cleaning would clean some of the yellowing since much of it is ground-in dirt, but everything I try, professional, bleach or vinegar, has produced minimal results. And there is no shine to it.