Can't put the plastic bobbin holder back into position

First make sure that the bobbin case locking lever is fully back, away from the bobbin case area. This lever is on the left side and to the back of the bobbin area. The bobbin case needs to be put in so the forked end of the bobbin case slides under the feed (towards the needle and the center of the feed dogs). Next slide the front edge of the bobbin case under the position plate. Then turn the lever towards you to lock the bobbin case in place. Make sure that the bobbin case can still move slightly. If it's tight, move the lever again and reset the bobbin case.

For pictures of replacing the bobbin case, see page 39 of the manual. Singer has PDFs of most of their manuals on their support page: https://www.singer.com/support . The current support page for the 9410 is https://www.singer.com/search/support?title=9410 . The current link to the manual is https://res.cloudinary.com/singer-sewing/image/upload/fl_attachment/Singer-Website-Library/outdated_product/SINGER_7029_7033__7035_and_9410_Sewing_Machine.pdf .

I hope this helps.

Cindy Wells

some videos
https://www.youtube.com/watch?v=51YIr4v8eoo

https://www.youtube.com/watch?v=8TgGzKsdXbU

https://www.youtube.com/watch?v=S1R8SUCBq5I
First, make sure the bobbin-winding spindle (located on top of your machine) has been pushed back to the left for sewing. If it is not in the correct position, the needle will not go down and pick-up your bobbin thread. ... Make sure the presser foot is up when seating the thread through the upper tension
https://www.singer.com/frequently-asked-questions

Perhaps a video here may help:

Singer 4423 Bobbin Threading

After you put the bobbin case in, release it, and then pull on it to make sure it is in correctly.
The gathering is called a "bird's nest", and is caused by the machine not being threaded correctly.
Rethread the machine top and bobbin.
Then, sew a test stitch on a scrap of like material.

it sound like the machine needs to be serviced by a sewing machine repair tech

If you lift up the thread holder, the bobbin holder is inside. Loosen the hand guide to stop the needle from going up and down. Pull the thread around the top thread guide and back into the bobbin holder. Thread the bobbin and move the bobbin over so the guage is "inside" the bobbin. As for the manual, the Singer Merritt 2404 is applicable to the 2430 if that helps.

The plastic bobbin case should sit on top of the raceway, it should slot in quite easily, once the bobbin case is in put the small metal clip at the top over to hold it in place.

Check you have the right size bobbin case the gap where the needle enters should be 13mm approx at the widest point. A lot of other pfaff bobbin cases seem to fit and can be easily be mistaken. I have two pfaffs and have accidentally mixed the cases and had a similar problem.

Update:  Today I took my machine in to get serviced - they replaced the metal bobbin I was using with a plastic one, that was a little less rattley inside the bobbin case, replaced the needle with a new, universal one, and changed out the thread with something a little higher quality.  They also adjusted the spring holding the bobbin case slightly, and now it seems to work fine.  I'm not sure how long it will last, but for now I'm good.  

I had the same problem and after looking on here and finding no answer I went back to my machine and found out what the problem was...ok, where the bobbin case sets in,the metal plate beside it needs to be fitted right close to the bobbin case, so loosen the screws(just two of them) that are in the plate(DO NOT REMOVE JUST LOOSEN) and slide the metal plate over some just enough to fit snug...NOT TOO TIGHT... if its seems to sew too tight loosen it a bit It worked for me, GOOD LUCK