A quick Google search found this:
No idea if he's still in business..
From: Mary Jean Collins
Sent: Tuesday, July 19, 2016 3:01 PM
To: [log in to unmask]
Subject: [ARSCLIST] Repair of Roberts 6000
I have a Roberts 6000, reel-to-reel portable tape recorder. It is not
working properly. I have many tapes that are close to 50 years old that I
want to play. I live in Washington DC. anyone on list who can help me out?
List was recommended by someone at LOC
Mary Jean Collins
[log in to unmask]