Hello,
  The fact that the switches were not working at all at first, the transmitter is telling you something. There was probably corrosion on switch contacts after sitting unused for so many years.
  I would not use that radio in anything that I cared anything about, especially a scratch built model. The only way you are going to know for sure about the radio is to have a few hundred successful flights with no problems.
  The fact that something did not work at first, probably due to corrosion, something else could go wrong and likely at the worst possible time and it would be a shame to find out the hard way that well I guess it didn't work, when you go to pick up the pieces of your scratch built airplane.
  I had a Super Seven radio, still do, that I did not want to risk on a new plane so I bought a new T7C 2.4 radio. Electronic and mechanical devices do not like to sit unused. Switch contacts, potentiometers, etc are all suseptable to corrosion. Use at your own risk.
  Just my 2 cents and only an opinion.

The Pamster