Re: grinding from neutral to reverse
first off check that you are in the correct neutral position / put the control lever in the neutral position then rotate the prop shaft (ignition off of course) \if you find any clicking either way then its not in the correct position, so disconect the gear shift cable and move the shift lever into the correct position
the shaft should rotate both ways with no clicks
now adjust the cable length to meet the shift lever ,then check both forward and reverse also check your idle revs if they are too low it will grate when engaging gear