The intermittent rear wiper seems to have cured itself, but now the radio has decided that it doesn't always want to mute when I engage reverse.

Anyone else had this? Know a fix?

Once reverse is selected, you can set the volume level. The next time it should be remembered.

isnt there a menu for that in the setup on the radio

sure there was on the stream one

There is an option in the menu, PDC vol.