Seems like rs-online only has that stock for Australia.
I think I'll order NE5532's.
I desoldered some chips from another part of the board and the two dead channels seem to work fine again at the first stage, where the signal was very weak compared to good channels - not in totality because I removed an op-amp from the end of the signal flow on each board. So I think I fixed it, just need 2 replacements for the chips I 'borrowed'.