Hi All: 1987 yr old looks great & had been running fine. Past few days - lost a lot of cool in freezer and body of refrig not cold enuf. Svc tech replaced defrost timer and terminator. Defrost heater checked out ok. There was a buildup of ice in freezer on back wall. Since svc - concerned still not cold enough. particularly in body of unit - temp regulator at d or e with number 6 or 7 on selector. Thoughts?