Two hammers on my upright piano, not literally touching, but so close as to set off my alarm bells while tuning.
Bad idea, but it's hard to resist the urge to try to bend one hammer away from the other. Doesn't work, but of course nearly destroy the piano in the process.
Next idea? Look up YouTube videos, discover these things called backcheck screws which are nearly impossible to see and equally impossible to reach. But it looks so easy on YouTube! Try to reach the backcheck screw anyway, and nearly destroy the piano in the process.
Common sense takes over, give up.
Another day? Look up these things called flange screwdrivers, find a kit on Howard but give up after finding that kit is sold out and nothing else will do. Piano is saved.
Another day? Find a screwdriver in garage, nearly destroy piano again.
Find another screwdriver and manage to undo backcheck screw a little but only succeed in making the key noisy. Can't actually move the hammer. Try to tighten backcheck screw again, nearly destroy piano in process.
Feel bad for piano, give up, come to PianoTell for therapy.
Piano lives to see another day!