As I know many of you are, I'm happy to do routine maintenance or work on motorcycle parts that are worn out, broken, misadjusted, etc. It's gratifying to address these issues and improve the bike's longevity, performance, and/or safety.
On the other hand, when I CAUSE the problem myself and lengthen the to-do list through my own mistakes, it makes me nuts.
The most recent "unforced error" occurred when I was changing the position of the EVT's control levers, which also changes the locations of the mirror mounts. With the mounts in the new position, the mirrors were at the limit of their travel and showing me lots of elbow, so I unscrewed them to adjust the angles and check for corrosion. As I took the left hand one off, unaware of the spacer, the spacer fell down into the bike and disappeared. I was almost positive that it never made it all the way to the floor and was trapped somewhere between the cylinder heads, maybe within the fins. Many bad words followed.
After looking all over the ground, I fished around with an extendable magnet from both sides of the bike for a long while. No joy. I left it alone for a few days, stewing. I figured I would have to pump the tank out and remove it.
I came back to it today and looked VERY closely. (Time away and looking again without preconceptions both help, at least in my case.) Where this arrow is pointing, below the bottom fin, I saw just a few degrees of arc that looked out of place.

I sent the magnet back in and was blessed by the Guzzi gods. Oh, joy!


This is a small example, but it was frustrating enough. I know these sorts of mistakes are inevitable, and I suppose I should be more patient when my lack of knowledge causes extra work; it's just learning after all.
Any amusing unforced errors lately? Ideally with a happy ending? (With experience, you likely have far fewer examples!)