I run two of these units on my layout. I replaced two smoke elements in the past few years. I went to order a few smoke elements from Lionel and they are now unavailable. It is a ( smoke element / 16 OHM / wirewound ) Part # 691RS16OHM / ALT 69RESC016 . Would there be a replacement I could use? I also run two of the A.F. SD70ACe's on my layout, they also use the same smoke elements / 16 OHM / wirewound.