Does My pH meter work?

I bought a $5 pH meter at Lowes, a Mosser Lee Standard pH meter, it is not electronic. It is basically just a probe that you stick in the soil, your supposed to clean it, then stick it in the soil and take a reading in 60 seconds.

The meter balances at 7.0, which is t he middle, goes down to 3 and goes up to 10 I believe.

I first tested it with some new Sta Green soil I bought, I put it in the peat moss pots and watered it, then stuck in the pH meter, it seemed to not move away from 7.0.

I cleaned it and probed the bag of soil, still 7.0.

Then I tested out a cup of miracle grow that one of my plants had died in, still wouldn't move from 7.0... very odd... then I watered the soil and the pH went to about 6.9. I brought up some lemon juice and drenched the soil with it and watered it again, pH moved down to about 6.2-6.3, I couldn't get it any lower no matter how much lemon juice I added.

Then I filled 2 more pots with fresh miracle grow, and 2 with dollar general potting soil, and watered. I took a pH reading on each of them. The dollar general soils pH were both about 7.0-7.1, and the miracle grows was 6.9-7.0... which is the weirdest part because I have read several places it starts at 5.0... though when I probed the miracle grow the meter was spasming weird back and forth to about 5.0, maybe a bit lower, then I moved the probe slightly and it went back to about 7.0.

I really dont think all those pH's would be that close to 7.0... anyone have experience with a pH meter thats not electronic?

Thanks.