I know this is a real longshot, but does anyone have access to a service manual for the original HP 6811B with the through-hole inverter board? You can find the Agilent and Keysight ones easily online, but the older HP has a different inverter and I desperately need a schematic. I'm sure it was only available in paper form, not electronic. All I need is the schematic and troubleshooting pages for the A7 inverter.