I loved my PE700 (pre-770) too.
Your machine is under warranty, so taking it to the shop is a great idea. However, you may want to do just one more thing before you do that.
You do not mention taking off the plate that has the size markings on it. There is a screwdriver in your kit just for that, it is very small and probably black and has wings (you will know when you see it). That indicates that the manufacturer trusts you to take this plate off the machine. If you cannot find that screwdriver, a nickel will work as well.
After removing that plate, (remember, turning right tightens and turning left loosens) check for that thread. If you can see it, use a tweezer to remove it. Look for small nips left over and remove them too.
Replace the plate BEFORE putting in your bobbin (voice of experience here). Make sure that the plate is in place very snuggly. A wobbling plate is disaster for your machine. If you cannot tighten, by hand (assuming you can reasonably use your hand) the screw any more, it is likely tight enough.
If there were no visible threads, then you must take it to the technician. It is time you made friends with your tech in any event. Ask them questions about your machine. A good tech will take time with you, become his/her best friend. Sometimes they can help you via the phone.
Pat, The Avid Embroiderer
BTW: God blesses me each day with love, hope and courage. I wish you as much and more.
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