I seem to have solved this problem. In the Settings dialogue of qjackctl I changed MIDI driver from "raw" to "seq", and now I can connect the keyboard to tractor etc. It seems to work, although I have not done very much with it yet.
I confess I hadn't tried messing about with this setting before, because I don't remember ever having altered it, yet the keyboard used to work OK with the computer. But logically, I suppose it must have been changed at some point. Anyway, thanks for all the help you have given. And I'm sorry to have made an issue out of something that was, apparently, so simple to fix. David -- ubuntu-studio-users mailing list ubuntu-studio-users@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-studio-users
