Hmmm... Wayfinder specific? or GPS trouble in general?

Try Maemo-Mapper, see if that works.

I don't have one, but here's the going advice for N810 GPS: Hold the unit with the screen facing forwards and the top edge directly up. The antenna's in the top edge, so it locks much better like that. Once a lock is acquired, then you can lay it flat on a table or whatever.