There is no syncro for Reverse. There are 3 different things I do that don't make it grind:
1. Put the clutch in and leave it in for a few seconds then put it into reverse.
2. Put it into a different gear then put it into reverse.
3. Put the clutch in and start putting pressure to put it in reverse, then let the clutch out just a little bit as you continue putting pressure and it should slide right in.
If it doesn'r pop right into gear and seems to be stuck, that is because the teeth on the gears are hitting together and not meshing like they should. It is NOT a problem. There, as stated above, is just no syncro for reverse. Because of this, you need to
1) put in the clutch in for a couple seconds before shifting into reverse to allow the gear to stop spinning.
2) shift to reverse
3) if it doesn't work or seems locked out ( gears aren't meshing), let out on the clutch and try again to allow the gear to obtain a new position.
4) try reverse again
It may take 1 or 2 times to get it in, it all depends on where that gears stops spinning and if the teeth will mesh right. There is again nothing wrong.