This machine was severely neglected - as you described - but luckily not badly abused.
All the electrolytic caps had to be replaced: only about 4 in the signal path, but 3 triple can types. Out came the cans and in went a PC board which took the 9 new radial PCB types. The three selenium rectifiers were replaced too.
A weak point on the G36 is the pushbutton assembly. The phosphor-bronze contacts break. Luckily on this one only one non-moving contact had broken, and I harvested a substitute from an old relay.
The counters also fall apart - they are made of plastic that becomes brittle. I plan on making an electronic LED counter to fit my G36 one day.
All three motors lubricant had dried out, so that was replaced. The motors are quite straightforward to disassemble though, and the bearing do not wear unless the machine is very, very well used.
This machine is super sensitive to head grime - and the heads are difficult to access for cleaning. When they are clean, it has a good frequency response, and a very stable stereo image.
The pinch roller got a substantial grinding down to expose soft pliable rubber.
The cathode follower outputs need to see a load of 100k or higher, otherwise bass response is affected. I did bring +24v Dc out on the now-defunct remote control socket, which can be used to power a solid-state output buffer if one is ever required.
Despite its condition, all the potentiometers were in good condition, not producing any scratchiness when adjusted. This is a bonus since the odd hollow shaft style will make it difficult to fit modern replacements.
The only adjustments are record level (operating flux) and record bias, so tape type is important - you cannot tweak the equalisation to suit dull or bright oxide formulations! Some people increase the bias + erase oscillator frequency from the original 70kHz, but I have no experience of whether this is really a good thing or just a change, not necessarily for the better.
There is also no comprehensive source/minitor switching. VU meters (true VU, with no peak indication) work on the record amplifiers only, and you cannot route the input signal through to the line-out for monitoring before record starts, nor do tape/source switching during record. Confidence monitoring only!
This is all because Revox expected such switching to be done on the pre-amp, and all monitoring to be done via the internal mono amp. The internal amp is in fact quite good, and is identical to that used in the Revox 40 integrated stereo amp. The inboard speaker isn't too impressive, mainly due to the cabinet's total lack of acoustics. But an external speaker or headphones (mono) does give very good sound. Originally the G36 had one of several variants of Philips dual cone 8" speakers, but years in a damp environment had caused this one to collapse, so it got a modern replacement.
Remarkably, new heads are still available. They are not interchangeable with the A77 & B77 heads. Genuine from Studer carry a nice price of around R5000 for a set!
This one's heads still have a good few hundred hours in them.
