Putting this here for posterity really, had this amp for a while, the zener shunt +- 10v circuit had failed. Patched that up but still didn't work, it seems both opamps TBA231 and 4558 had also failed. Decided fairly easy to substitute a 8 pin dual opamp for the TBA231 using the top part of the socket, as the 231 has so many compensation components. That looked good, and one channel worked but the other not. After a lot of poking around D1 and D2 are on the PCB silk screen picture in the service manual (I downloaded from the crown website, it does seem that there are different versions), but not in the circuit diagram I found, which has LF357s. Remove these treacherous little chaps as well, and it looks like the amp will work.