We have a male chaffinch with 'bumble foot' but he's feeding OK. It's several years since the greenfinches succumbed, they are slowing returning. A brambling appeared with the chaffinches this morning :-).
I use
cif in boiling water with a toothbrush and long thin kebab stick 2 push any old feed out or soak in
Milton then use brush and stick and drain well. I also move feeders around the garden which can cause confusion

. Mum never moves her feeders and rarely washes them but she doesn't have any birds with disease ........ unless the local cats get them.
We don't have as many of any variety these days, I hope it's because more people are feeding in the area.