(I am merging my 3 replies together)
I have spotted the same issue. Instinct tells me I should trim the bottom section to match 20m and then tune the 40 with the end shortening (I just wind this up and tape it up with a insulating tape so I do not have to cut).
I wrote to LNR for advice, let’s see what comes back as a reply…
— Update: reply from LNR —
“Looks like the 20 meter side is too long, start by trimming the radiator by about 3 inches at a time, but be careful”
— end of quote —
So, I will give it a chance, I am just surprised it is to start with 3-inch trimming at first… I am not that courageous, I will do less…