Playing with the ATU showed it was very difficult to get a decent match anywhere, suggesting the now soggy vegetation near the balun is probably drooping onto the window line section and detuning it. I have managed to get a usable match on 40m, so have popped up there at 2W. The system went straight into transmit with the results as below
Now into the receive cycle, lets see where I can get today
UPDATE: The rain has stopped (mostly) so I managed to get out and take the shears to the mass of Ivy that has, seemingly in the last 12h, utterly overgrown my balun and lower section of window line feeder. With that cleared I can once again get a match on 10m, so have QSY'd up there to see what can be done.