I have seen that as well. On my 47 the panel the edge was rounded and the seal was stapled on. My panel was crunched so I sourced a replacement original. It had the j slot which I presume was a later improvement to make the seal easier to install and hold. The j slot was cut off of my replacement panel so I could use a flat piece of seal. I have not seen the seals reproduced and figured to be using a generic rubber seal and adapting it to fit, My stapler is not capable of that thick material so it will be glue and screw. In my prowling the internet during the last week or two I have seen these panels are being reproduced. It was only a few hundred for the piece which makes it reasonable depending on how much metal working you have to do. Since I have my issue solved I did not pay attention to who was selling that item but there are only a dozen or so sites that sell this stuff. I think they all get their stuff from only 1 or, in some cases, 2 suppliers.
