What you need to do is back it up ASAP and figure on it not working much longer. Everything beyond the chance to do the backup is gravy on top of that gift of chance.

Tapping all the sides is one thing, but dropping it from any of the sides is another. If you manage not to un-park the heads without damage that's great, if not, it's likely bad.

Lifting it up on an angle from front or back was the usual method back in the day. Thumping the heads loose without banging them around would be best.