@doctorm :
Hi.Fi Dido is very well know vintage audio source and could help you:
JC-80 DENNESEN - Used Audio Purchased & Sold At A High Price Hi-Fi Hall
the page is full of pictures even better than an operation manual and in the last two pictures and in its left side you can see a red plastic parts with tiny white " sliders " parts that seems to me could be to change gain/impedance for LOMC cartridges. Those plastic red controls are where are the phono inputs at left side looking from the face plate.
I think that you could not need any manual but you can must following behind that manual.
R.

