Rotary hooks rotate twice every time the needle comes down, so if you run your machine at 700 stitches per minute the hook spins at 1400 stitches per minute (SPM). The interior of the Hook has a rail that slides in a raceway and holds the hook together. There are no bearings, so the rail and raceway are metal on metal. This is the only point on the machine that most manufactures recommend you lubricate every four hours of use. Rotary hooks may need to be replaced at around 3 to 5 years, depending on use and maintenance of the machine.
Symptoms that could be caused by a worn or damaged Rotary hook are:
Note: These same symptoms may be caused by other issues also.
Note: Most Toyotas and Tajimas will sew with generic Rotary Hooks but may sew better with an Eccentric Hook. The difference is that the timing point lifts to meet the needle so that the needle does not have to penetrate the cloth as far. This makes the machine sew better with caps.
eccentric 2 a: deviating from a circular path
Note: Rotary hook prices rages from about $18.00 to over $300.00 a piece. Quality does make a difference.
Here are two examples:
My suggestions for Rotary Hooks from SEWMANYPARTS.com:
Note: Refer your your parts books and manufacturers suggestions for your machine.