How to recover signal repeated throughout other signal?
This is a source separation problem, which, in general is quite difficult to solve. One way to attack it is to use non-negative matrix factorization (NMF) with short-time Fourier analysis. Please see this question and a sample script here.

The overarching idea is to try to isolate your component sounds A, B, C,... using a time-frequency decomposition (or, perhaps, some other kind of subspace analysis using a different transform, like wavelet transform). 

If the components don't always all play at exactly the same time, or have different onsets, you can hope to separate them temporally. If they don't all have identical frequency content, you have some hope of separating them in frequency. Or, a combination of both, which is what NMF of the STFT achieves.