Getting the most out of an inexpensive chromatic button accordion

Bought a chromatic button accordion and fixed some things. Contents: 1:00 - Description of the accordion 4:10 - Removing the fifth of the dominant seventh chords 11:04 - Adding an extra bass register 17:02 - Improving the treble-bass balance (NOTE: Regarding the loosening of the reed blocks to improve resonance (22:30), I now have my doubts about this and have tightened them quite firmly. I now think this is better since the vibrations travel more easily through the material when it is tightened. Apologies for the dissemination of fake news, and I still don't know what's fake and what's real!) Technical details of the accordion: Barcarole Professional Treble: 5 rows, 83 buttons (6 dummy buttons) 46 notes (C - a`` on lowest register) 4 voices: 16-8-8-4 11 registers Bass: 120 buttons 4 voices: 1: G, - F# 2: G - f# 3: d - c#` (chords) 4: d` - c#`` (chords) 3(4) registers: 3+4, 1+2+3+4, 2+3 (after fix, also 1+2+3) Note: dominant 7th chords consist of all 4 notes (after fix, only 3, without the fifth)