So, what happened here? You needed more money, a lot of people seem to have upgraded in response, and not a peep from anyone?
Did the money actually go to helping the forum at all?
I think there's been some good solutions offered. vBulletin, for example, or XenForo
Another solution would be to dump all of the information on this site onto something like archive.org, then add a new section about tutorials, information, tips, how to, Chord shares etc, and put those into a locked section, and then create a separate "discuss this" button that takes you to a Discord or simple message board, which self-deletes every 90 days when timed out.
Maybe someone can go through what is here now and transfer the useful information posts into the new locked section.
And if you have questions about the post, just pm the op and they can update the op with additional information in case others have a similar question. And have Inboxed auto delete 30 days after reading.
You could turn UU into strictly an informative site, full of user-contributions, without any comments or replies, saving those for PMs and Discord chat, and relying on the Ops to update their posts with relevant information from the feedback and questions they receive
You could also give users the option to click an option in their post or reply that says "self delete in 30 days" for posts and replies that aren't meant to be important lasting information for generations