Hello QUAD
I have also STAX technical papers and STAX original service manuals if I can help you let me know !
On a personnal point of view now ,I saw that you have a modified pair of ESL63 can you tell me more about them . I have probably refixed more than 500 ESL 63 and I still love work on them !
I also do "upgrade" when customer is asking for .
Have a good day
QUADESL63