Why won't my Bernina Activa 140 sew the blind hem stitch?

https://www.berninamanuals.com/Bernina_Service_Manuals.htm

(not free)

Perhaps the manual would be helpful:

BERNINA activa 210 Support BERNINA

You may want to download and keep this manual. A lot of manuals for older Berninas are no longer available.

...

try adjusting the top thread tension just a little and then sew on a scrap piece of fabric till the bottom stitch look correct.

12 wt thread generally will not work well in the bobbin...


"Aurifil 12wt Thread
Aurifil 12 wt thread is ideal for hand quilting, big stitch hand quilting and machine quilting. 12 weight thread creates a more defined and often primitive look. It's great for designs that use a longer stitch length if using a machine. When machine quilting with 12 wt thread, use 40 wt in the bobbin, increase your stitch length, lower your tension, use Topstitch size 90 needles and stitch slowly."

it's very possible that the machine is slightly out of time & needs to be service at a sewing machine shop
is the fabric & thread & needle compatable with each other?
did you use every thread guide when threading the machine?
is the bobbin in correctly?
is the bobbin warped?

Do you mean a presser foot to sew rolled hem or shell hem edges?

If so, the Bernina website lists the accessories here:http://www.bernina.com.au/product_detail-n25-i61-sEN.html

Bernina feet 68 and 69 are rolled hem/shell, just different widths. However, I think the feet for the Activa are the new 3 digit numbered feet? I know there is the old style and new style attachment system for Bernina feet, if you look at the presser feet you got with the machine, they will have a code on the front of the foot; buy any new feet with same code format.

As to where to buy, I always start with the manufacturer/distributor in my country first. So start with www.bernina.com, go to your country, then "contact us" page and give the local office a call. They should be able to confirm the exact foot code you need and sell it to you or direct you to a local dealer who can.

Some machines will not do any of their automatic forwards and backwards movement type stitches in reverse, are you trying to reverse in straight stitch or a more complex stitch.

The Activa is a late model quality machine, do you have a Bernina dealer locally you could ring up and ask or take it to?

Check the manual to be sure the needle is inserted correctly.

Also - check the needle to be sure it is not bent and that there are no burrs or nicks on the throat plate.

Berninas hold their value and it is worth investing in the service fee to have the machine thoroughly gone over by a Bernina certified tech.

Try pulling more thread out before you begin the seam - about 6". If you can hold the threads while you take the first few stitches that helps too.

There is also a tension adjustment on teh bobbin. It's just a little screw. Turn it about 1/4 to 1/2 turn and try again. Adjust as needed a little at a time.