A common job that i get asked to do is a Bernina 707 cam gear replacement repair. The plastic gear inside gets old and develops a crack. The tell tale sign is that the machine gets jammed or it will run for a few stitches and then stop. The crack in the gear makes the teeth open up therefore making it stick. Here is a step by step guide on how to replace it

Bernina 707 cam gear replacement

Bernina 707 cam replacement
Here you can see the split in the gear. Luckily parts for the Bernina 707 are readily available.

Bernina 707 cam replacementHere is a nice brand new shiny replacement gear!

Bernina 707 cam replacementYou can see the round, dark hole in the gear and above that another hole. Both holes have a screw inside which need to be loosened.

Bernina 707 cam replacementAfter the screw’s have been loosened the cam shaft needs to be removed. Start this off by using a screwdriver to gently push the shaft. There is an exit hole for the shaft on the rear of the machine.

Bernina 707 cam replacementHere you can see the shaft sticking out slightly from the back of the machine.

Bernina 707 cam replacement

You may need some tweezers or pliers to start pulling out the shaft but be careful not to damage the end. Pull the shaft all the way out taking a note of the position of the groove.

Bernina 707 cam replacement
Now the complete cam assembly can be removed from the machine.

Bernina 707 cam replacement
Both of these screws need to removed as they hold the plastic gear in place.

Bernina 707 cam replacement
The gear can get a bit stuck onto the cams so gently prise them off with a screwdriver

Bernina 707 cam replacement
Give the cams a bit of a clean up but keep the order the same!

Bernina 707 cam replacement
Align the cams in the same order and position on top of the new gear. There are two holes drilled into the metal part of the gear which should be positioned anther the two holes in the cam.

Bernina 707 cam replacement
Tighten the screws a little bit on each side and keep alternating until its nice and tight.
Bernina 707 cam replacement
Reposition the gear and cam assembly into the machine.

Bernina 707 cam replacement
Re-insert the shaft until it is flush with the rear of the machine and then tighten up the two screws to hold the can assembly in place!

Thats it!

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