Hi there,
I just had the same problem a couple of days ago. I tried the usual suggestions, all given here - nothing worked. By the time I'd installed the third new needle and it still didn't work, I called my dealer. She asked me to turn my computerized machine off, unplug it, wait a minute or two then plug back in and turn back on. Kinda like rebooting a computer. Would you believe it WORKED!
Why? She didn't know, said for some reason, "It just does." All be darned. If your machine is computerized, it might be worth a try. Best of luck to you.