......I finally managed to get it right.....measuring 1500m on a stretch of road in East Bowral. No idea how or why I couldn't do it yesterday, but there you go! Nothing wrong with Mr G-armin after all!
Firstly, I walked 750m out & back....even getting the 500m mark correct. Then, to put it all to the test, I set Mr G-armin for 1500m & jogged the full distance.....and all the markers lined up as they should! I managed to do this without dropping any more dollops of paint, but need to remember that 500m is just short of where I left a splash yesterday. I'll put a dot of something next time I'm in the area.
....I must have left Mr G-armin on while driving home...the long straight line!! How could he do that??