Update on the 222122k.
I've done a bit of cleaning because it got worse.. when it'd turn on, in addition to the 'bang', it would sound as if the whole lower keyboard was pressed together, until it fades to only one note (low C) which remains stuck. I've opened it up and all, I don't see where the issue is coming from.
Is anyone familiar with this issue? I really don't intend to get rid of it...
I didn't get many good pictures of it when it was open I'm sorry I can't show the connectors or anything in detail.