Tandberg was considered a very high end brand, manufactured in Norway, and they were great machines when they were being sold. Unfortunately now, they are problematic machines, usually with multiple problems when they come in for servicing.
Pre- 1973 decks. I refer to the rough year of 1973 when Tandberg switched to a logic controlled pushbutton controlled decks from the pushbutton, mechanically controlled ‘joystick’ lever of the decks made in the 1950s and 1960s. The problem is that Tandberg used a lot of cork and rubber in their decks, the cork being used in the reel tables for braking and takeup torque control, and as you can imagine, cork deteriorates over time. More importantly, the cork thicknesses were metric, and most replacement cork found in North America is the wrong thickness, and won’t work as a suitable replacement. Trying to rebuild a reel table on an older Tandberg is very labor intensive, and usually with variable results of success.
The same holds true for the belts and idler wheels that Tandberg used. The idler wheels can be rebuilt, and belts are available, however the costs add up quickly when servicing these decks.
Post 1973 decks- Tandberg switched to logic controlled, pushbutton transports around 1973, and they were state of the art at the time. The problem now is, that between bad capacitors, and trying to troubleshoot discrete logic transport boards is also labor intensive and very time consuming. Tandberg used some custom made motor speed control chips in certain models, such as the 10X, and replacements are impossible to find.
Tandberg also used Rifa and Frako capacitors in their audio circuits, and many of these are now failing, and need to be replaced. By the time you add up the costs to service the transport and overhaul the electronics, the cost for even a basic service becomes cost prohibitive for many Tandbergs. When the heads are in good shape, they are nice sounding decks, however.