There are many different versions of the Krikit with different tension ranges depending on application and use. Thus you need to pay attention to the specific model number and the color of the plastic doohicky the gives you the reading. II find it interesting that Gates recommends 28-40 lb belt tension, but their Kriket Gauge Tension meter has a scale range of 40-150 lbs. I don't think I would pay $40 or more for a gauge that will not read in the scale I need.
Wonder if anyone has tried using the free mobile app on their phone?
Here is a photo of mine which is the correct one for bicycle compatible Gates belts. It has ranges in both Kg and Lbs. not the readout range on the frame is 30lbs. to 150lbs. It sounds like you might have the been looking at the right one as the two marks below 50 each represent 10 lbs. You can easily infer a tension lower than 30 by guestimating where the next lower mark would be or you could carefully measure the distance between marks and put a metal friendly permanent marker line with the 25 lbs mark should be. I found right between 30&35 lbs. seems just right.As I no longer have a bike with a gates belt, I would be happy to part with mine for $35 including first class mail shipping within the USA.
Please get in touch with me privately through the message system here on EBR. If you have not done that before, just hover your cursor over my name below my profile photo and click on "start conversation". Note inside the original box is the instruction manual. Many have tried the app that measures the frequency when you strum the belt to determine tension with some success and some failures.