I've added a buck boost transformer inline to reduce voltage from 240 to 220 , this doesn't seem like much but the 240 moves around depending on demand and sometimes could be 248 or 233 , the elements from Toper are 220 v , since reducing voltage they have never died . The trade off to this is a little longer roast times by about 2 min .

Interesting! Where are you buying replacement elements? How often were they burning out that you had to step voltage down for increased life?