I think you should find out which parts of the circuit are working and which are not. And I agree with @analogoutput that you should concentrate on the analog side of the circuit first.
One way of tracing AC signals, if you do not have any specialised equipment like an oscilloscope, is to use an audio amplifier. It basically boils down to that you probe the circuit and listen whether you can hear a signal where you would expect one. This should work with an oscillator as all it will produce (most times) are signals in the audible range. You can step through the circuit and maybe find out where the signal gets lost or dampened more than you would expect.
So what you can try is:
1: make a probing cable that has shielding and a signal wire with a connector on one side which fits your amplifiers TAPE or CD input (stay away from PHONO et al.).
2: connect a capacitor of say 1 - 10 microFarad ( use whatever you have, the value is not that important as long as you are in the sub 50 mu-area) to the signal wire on the other end of the cable.
3: connect the wire’s shielding to your amplifier. Use e.g. a crocodile clip, alligator clip, or my favourite gold plated hand made caymen clip for that. Do not use a tube amp here, as this can be problematic/dangerous given some of their chassis may carry a voltage.
So a simple modern (transistor based) amp will do fine.
4: try the cable: hold your finger to the capacitor: your amplifier should humm. What you hear is mains humm which you as a person receive because maybe unbeknownst to you, you act as an antenna for.
Now choose a moderate volume on your amplifier.
5: hold the capacitor’s end against any point in your circuit you expect to find some audible signal.
You should hear this via your amplifier. If you want to continue to another point in your circuit to be on the safe side you can short the capacitor to make sure it is not charged. I’ve found that with a small capacitor value (a few micro Farads) this is not necessary.
6: Now systematically trace the signal to where it should go and hopefully you will find the problem.
Keep the probing cable, you will likely need it again for a future project.