DYNATRAC ITHACO 399 lock-in amplifier instruction manual

[Jm Douroux]

I bought a lock-in amplifier ITHACO DYNATRAC 399 on ebay. This well-designed material still works but the manufacturer no longer exists.
I would like to calibrate it and use it better. Does anyone have the instruction and maintenance manual? Now that the price of this material is very affordable, it would be nice to put the record on the internet.