This is great news, Lex!
I am glad that this was indeed the source of the deafness. I still hold out hope for mine as well, but in the meantime, I'm preparing for plan B; a separate cavity filter input with circulator, and a separate amp. I need to look at my parts box, but I might already have the filter and I know I have a circulator. Of course, the circulator being a non-linear device, I don't know how well it would work in front of all of this. As such, plan C would have me put a more typical directional coupler before and after the filter instead, just like the existing filter.