I'm trying to lock my stitches for machine quilting by sewing tiny stitches for the beginning and end. I notice that the bobbin thread shows on the top when doing these tiny stitches. They disappear when I gradually increase the stitch length though. I've adjusted the thread tension to the lowest number (ie 0) but the bobbin thread still shows. What else could I do to resolve this issue?

check that the bobbin is in the right way, I had this problem with my new husky and all it was, was the bobbin was in clockwise instead of anti clockwise,

Erm...how can I check if the bobbin is in the clockwise or anti-clockwise position?

is you bobbin horizontal or vertical. either way if you pull the thread watch which way it turns the bobbin, if it goes clockwise as in the hands of a clock, turn it over so the thread goes the other way anti clockwise and give that a try, some machines like mine goes better in the clockwise position, others in the anti clockwise position. it is all trial and error, also check that the top thread runs smoothly as this can also affect the tension.

Thanks. I tried switching the position of my bobbin to anti-clockwise and the thread doesn't show up on the top anymore. But now, the top thread shows on my backing! Arrgghhh....

Have you tried pulling up the bobbin thread to the top of your fabric then holding it taunt while sewing in place. Thats what I do with my long arm because has no feed dogs and works great. Also my Janome 8000 has a "locking stitch" that does about 4 stitches in one place before sewing. Not even tiny stitches- just in place. Good Luck

Yup, I always pull my bobbin thread to the top and hold it in place while locking the beginning stitches. Think I'll read the manual to check if my 6260 also has a "locking stitch" function. This appears to be able to solve my problem. Thanks.

maybe now you need to adjust the tension on the top thread you may have slackened it of too much. its all trial and error. every machine is different and it is a case of what works best for your machine