Hi Karen,
There are usually a couple of dots before the '0' and a couple more after the '10'.
If you turn the dial all the way in one direction, then slowly turn it back again all the way, counting the clicks, you will be able to find the approximate position of the '5' mark by halving the number of clicks and turning the dial that number of clicks. Then by moving it three clicks at a time you will get the approximate positions of the other whole tension numbers, either side of the '5'.
Hope this makes sense and helps you.
Regards,
Sue, September 2012