Bits and bobbins.

I spent a few hours shortening several pairs jeans /trousers using my Singer sewing machine today .While halfway through a trouser leg the machine developed a knocking sound which turned out to be a bent needle. I  changed the needle and away to go, or so I thought, no way. The problem was now I couldn't pick up a stitch. What was wrong? a bit of head scratching and reading of the Singer manual & I  found the solution, I'd only put the needle the wrong way around. Duh! Even Oilyrag gets it wrong sometimes.