Revoxes are usually side-splittingly expensive to repair, although very simple to disassemble.
The main issue is the cost of record heads, thanks presumably to the Swiss franc/German mark.
The mechanical engineering is pretty good but the electronics are not up to Japanese standards. With A77 there's a serious problem with plastic parts being perished by the heat inside -- so setting up the record equalisation or whatever can end up as a soldering job when you have to replace most of the potentiometers.
You need a repair place within driving distance. Shipping would be expensive and risky due to weight and fragility (you'd be amazed how badly freight companies treat your stuff).