Having trouble with bobbin case catching upper thread.

Try a sharp new needle first (and check it is in correctly, flat side to the rear for modern machines, or as per Manual )... this is often enough to resolve skipped stitches

Did you have a recent Jam ??

Check for rough patches and burrs everywhere the thread passes... use a fine emery board to polish

Tease out a QTip/Cotton bud etc to be a little fluffy, then trace all over the metal and plastic regions and the bobbin case… it will likely catch and show you where the burr is

NOTE : If it is under warranty, do NOT attempt to do too much, lest you void the warranty
If you have had a recent jam, then this suggests timing may be affected

In any event..... here's how to check

Unplug machine and remove all thread

Remove Needleplate, Free Arm and Bobbin Case so you can watch the needle easily

In correct Timing, the needle will be at the lowest point just before the tip of the hook passes behind (to catch the top thread)

If the hook passes too soon or too late, it will need re-timing...

This short VIDEO shows how a stitch is formed… if the hook is not in the correct position, it will not catch the needle thread

https://www.youtube.com/watch?v=ML8CMNzW6Tg

Here is a basics guide to know when and how, and whether it is time to hand it off to a trained Tech

https://www.youtube.com/watch?v=ZsebAKZxmU0