Steele Rubber has a correct molded repro of the barn door rubber for the TF series, a bit spendy but perfect - if it's not listed on the website give them a call, they do have it
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics