My newest treasure was a two track unit, whereas my tape library, accumulated during twenty years, was in four track format. Since the tape heads needed replacement anyway, I decided to modify the unit into a four track machine. The unit had the usual problem with the older Revoxes, the tape erasure was a little weak, at least with the original erase head. I managed to get a copy of the Service Manual plus some smaller parts from the local Studer representative at a reasonable price. Taking the deck to pieces needed some courage, but everything was pretty easy after I found out which wires to unsolder in order to separate the upper and lower chassis.
Most removable wires go to the terminal strip near the power supply capacitors.
Some wires go to the selector switches S5 and S6. If you remove the switch wafers of S5, no wires from it need to be removed. The wires going to switch S6a must be unsoldered. Be very careful to make notes of the position of the different wires. Once the unit is in two pieces, all the parts are easily accessible, even changing a switch contact is relatively easy.