Tandberg Unit needing some love


Hello Everyone,
I write this for a very good friend who has a Tandberg 1055 unit that has low pre amp output on one channel. This is a unit that is about 40 years old. He with my help is looking for someone with knowledge and skills to repair it. He resides in the 07764 zip but of course can ship the unit. We have tried several leads but come up empty.
Thank you for your time and anticipated help   
wmwman