Changing the needle makes sense to me. I broke a needle while sewing, changed the needle, rethreaded, etc. and got a terrible clunking sound when I tried to sew again. Fearing I had affected the timing, I brought my machine to the repairman. He went through my machine, cleaned it, oiled it, and tested it. When I picked it up, he told me that the problem was solved when he put a new needle it. The new needle I had put in was bent!