I have a WS4 since last year and shortly after I got it, the compass started acting up, just like you described it. That`s when I decide to read the manual....LOL
Anyway, the manual says that in some instances, the compass needs to be re-calibrated. It is actualy a good idea that the compass to be callibrated periodicaly. Here is how to do that:
- Press MODE untill COMPASS is shown
- Hold SET to start
- Keeping the watch level and dial/display faceing up, rotate the watch twice then press MODE. Make sure you take about 15 seconds for each revolution.
- Next push START or STOP button to set (increase or decrease) your declination angle which is specific to your location.
- Press SET to finish. The watch will show on the display OK CAL if the calibration was succesful or CAL FAIL if the calibration was unsuccesful. If unsuccesfull, repeat the steps above.
PS
Regarding the declination angle. Leaving the settings at "0", the compass will read the magnetic North. By entering a declination value, the compass will read the geographic North
Unfortunately, the manual only gives the values of 40 or 42 cities from around the world. But you`ll find the location you want on the internet.
Hope this helps