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6. Remove the rear upper and lower arm covers.
7. Release the tension from the z-belt by loosening the belt tensioner screw with a 4mm Allen
wrench.
8. Remove the timing pulley by punching out the roll pin. The manufacture recommends that the roll
pin not be re-used after it has been removed.
9. Remove the snap ring from the front of the bobbin shaft.
10. Tap the bobbin shaft toward the rear of the lower arm casting to release the pressure from the
compression spring. Use a rubber mallet or a brass drift so as not to damage the front of the
shaft.
11. Replace the compression spring and the rear linear bearing.
12. Replace the timing pulley on the bobbin shaft and make sure that the rear radial bearing is in con-
tact with the pulley.
13. Push the bobbin shaft back into the lower arm until it makes solid contact.
14. While holding the shaft in place, push the front radial bearing onto the shaft and insert the retain-
ing clip. This is usually easier with two people.
15. Install the rotary hook, rotary hook guards, rotary hook support, and the needle plate.
16.
Install the z-axis timing belt and tension the z-belt to specifications following the procedures in the
Z-Belt Replacement and Tensioning section of this document.
17. Install the rear upper and lower arm covers.
18. Install the arm cover and replace the rear screw on the other one.
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