I'll see if we can have another look at the knobs again on the board, just to be 100% sure. Unfortunately, it's hard to find a brand new model in store around here since there's not many places around that sell them here (plus lockdown is a pain right now). We might've just found someone who could possibly take a look at it though, so there might be hope!
Does yours start vibrating on all three settings? It does seem that there is life in the sustaniac, I just can't understand why it doesn't hold notes like it should. Currently it just plays like any old guitar.