LDM-815 DIP METER troubleshooting

I ended up getting an old DIP METER.
The dipmeter is a popular radio measuring instrument among amateur radio operators.
It is a Colpitts oscillator composed of an LC resonant circuit and has been widely used to measure the characteristics of resonant circuits, filters, and antennas using resonant frequencies.
It can also test transmission lines, signal generators, and measure the inductance and capacitance of components.
This began operational testing of Colpitts' plug-in coils.
But this did not work due to glitches.
I obtained and analyzed its circuit.
However, the transistor used here operates normally even if it is broken or damaged.
However, the Colpitts circuit did not work.
One day, several months later, I reviewed the circuit again.
The cause was a short circuit between the layers of the air barricade.