Following Forgebear's schematics, and the advice on attaching the ground/earth cable you should find everything working. A piece of advice, though, efficient electronic contacts can depend on clean terminals. If I were you, I'd get a can of contact cleaner, and some absorbent lint free cloth and give your MFU and other parts a good clean up (with the battery disconnected). AK47s may well work with a receiver full of detritus, but electronic contacts and junctions can begin to work erratically- or not at all- when dirty.
Good luck with all of that

"Get your facts first, and then you can distort them as much as you please"- Mark Twain.