Hi, you can actually set this card up to work without the hybrids, but it takes a little re-routing.
Only LF and RF (ST1) and Mono are de-balanced via the hybrids, but in each case a standard buffer is present for these circuits.. A link change activates these, but they input on different pins, so this would need to be changed.
Run mine without hybrids.. and have them for sale!
It's worth getting the 4000G service manual from this site, 99% will relate to your console in terms of servicing.