This seems to be a common problem with aging VU meters. It's possible that the movement mechanism has decentered or possibly the adhesive used to keep components in place has deteriorated and migrated to the movement area obstructing the pointer mechanism. Here's a link to a Thierry Martin article detailing a VU repair - it is translated from French to English.
I believe that your meter is shared with A-3300S and 3300-10 but NOT the SD, SX or R of either x300 series models. Sam/skywavebe got me a replacement for one of mine that had the needle broken off.
If the meter is stuck with the power off then it is a movement issue and there should be a lot of parts available on the bay and if no place else Audio Pros where I get a lot of stuff from Vince. He always wants pictures though. If you need a meter, I have about 200 of them but a lot for cassette decks and such so not always what you want.