It was very easy to find the parts I needed at reasonable prices. I will use this website again for grill parts.
Aspen pad-bw4000/wh4002
Bw4000-02, fk401/02, wh4001/02, wh4401-03, wh4801-03 21”x29”
Buy this part and as many parts as you like and pay only $9.99 shipping, within the Contiguous United States.