J n J

We've got about 80,000 mi on our 1999 AWD Legacy Outback. About 3 months ago, the speedometer would suddenly stop working, then start again. This continues. My mechanic checked the continuity of the wire from the sending unit to the speedometer and it was fine. Occasionally, a quick stop or start will jar the speedometer to work again. Anybody have this experience? Anyone able to provide some solutions? I'm using the tachometer to ballpark my speed, and it doesn't work all that well.