There is a thread about AK's technician. There are also a lot of threads that are about repair of the G-9000. Search: G-9000 repair, G-9000, Technician, for a start. Those links will lead to others. A lot of techs are backed up. I scheduled with mattsd last winter and I just last week I sent my SX-1280 off to him.
Having heard my opinion on this subject, you can understand I have a lot of respect for these wonderful old machines and I believe it is worth every penny to get them brought up to spec. If you don't believe me, go to Ebay and search Sansui receivers. You will see that people are willing to spend large amounts of money, even on units that are not working. Just for fun, I have been following a Sansui Model Eight on Ebay and at 5 days out, last night, it was at $395.00. This is why when my quirky Model Eight gets too bad, I will be sending it off for repair. I will consider it money well spent. My plan is to have a working receiver for every room I want a system in. In addition I want to have a spare unit for every working unit. It has taken quite a few years, but it is almost done.
I wish you luck with your "Big" G. Keep us up to date on what you decide and how it is going.