Hello Donna,
It is difficult to get it right on a serger because it can be a three of four thread, it is very unusal for an overlocker to go out of time, turn the balance wheel so the needle goes down and then starts to go back uo, the hook should be just above the eye of the needle, if it is not you need to slacken the bottom drive bar and move it round until it is just above the eye of the needle, it can take quite a time to retime these machines and it may take you quite a few attempts.
drivewithken@blueyonder.co.uk, September 2008