This video might be helpful
https://www.youtube.com/watch?v=xbM_Eat0VmI&ab_channel=Craig%E2%80%99sExpertTips
This problem seems to be well known for 8610 8620 etc and there are several videos explaining how to fix the head missing symptom.
let me know which, if any, solved the problem so I can make a note and refer other users to the correct procedure.