Using the correct pressure foot???? and that the needle is in correctly.

On the machine that was a needle breaker/not timed correctly i watched this video and fixed the timing my self. Lol of course since it was the machine i had found abandoned on the road i figured it wouldnt hurt it or my pocket book if i tried to do it my self. Hahaha luckily a few hours of work and oiling yielded me an awesome machine. Http://www.youtube.com/watch?v=fzhR6PNlI4E

Its not too hard and he explains it really simply.

You also might check that she got the right type of machine needle. Some are longer or shorter. I think I would take it to someone you trust to have it serviced. My machine always purrs like a kitten when I get it home from being serviced.

Great video, but if you scroll down to the comment by Bob Banks, it appears that his luck might be temporary.
Bob Banks wrote:
"Nice video, but the timing was adjusted in the wrong place. The gear you moved tightens on a flat spot on the shaft. It will eventually slip back to the flat spot where it is supposed to be. However, at the RIGHT end of the shaft is the proper timing adjustment. There is a gear that the belt wraps around. It has TWO set screws. Two set screws are required because the shaft is round there. That allows full timing adjustment."

That's true i did end up moving the gear with two screws. Once loosened it does move freely like a puppet with no strings.

Oh my, I NEVER loan out my machines!

I'd check the bobbin case, it may be bent and impeding the hook. Also feel the hook and watch the needle go up and down without the bobbin case. Just my two cents...