Bosch 100 ft. Blaze Laser Measurer

I purchased my Bosch GLM100-23 about 10 months ago when starting a job to finish out my unfinished basement. When assembling sections of my stud walls I use the GLM100-23 to measure the distance between the concrete floor slab and top plate which is attached to the bottom of the floor trusses; however, I drop a plumb bob from the front edge of the top plate in several locations and snap a chalk line so that I can get an accurate measurement. When I stand the Bosch GLM100-23 right at the chalk line the dot from the laser very often hits the underside of the top plate as much as 2 inches out of plumb in 9'-3". When I check the floor slab with a straight edge it is no more than a few hundreths of an inch out so I don't think that is the problem. What can be the problem? When I build my stud wall sections to the dimensions I get with the GLM100-23 they are always too tall and I have to drive them into place with a large hammer. If the discepancy was consistent I could adjust the height of my stud panels. I am flummoxed.

Bought this to help me accurately measure baseboard and trim molding. It took me a few minutes to figure out the click wheel setting for the format I wanted.

There is no click wheel in the GLM100-23. Even in the diagram the clickwheel text doesn’t point to anything

Bosch GLM 15 Laser Distance Measure and it was a MUCH better design, and MUCH more dependable to use. This one, the GLM100-23 Blaze, is very poorly designed in the following ways: 1. The raised button for changing the accuracy, which is just below the red arrow button, is just too easy to hit instead of the red button when you start and stop a measurement, because you are looking for the red laser dot to ensure you're taking the right location. This device needs to be able to be used "blind"; You don't want to also look at the device to see that you're hitting the right button, you're doing it by feel, and the raised dot for the accuracy change is too danged easy to hit. It wastes a tremendous amount of time. The GLM 15 had no such problems. 2. The spring that holds the battery is not strong enough to maintain electrical contact when the unit is bumped, or perhaps something else is loose in it, because the thing turns off randomly when in use, so it is a frustrating pain the rear to use. The GLM 15 had no such problems. 3. The GLM 15 would save the previous reading, so it was easy to compare two successive readings, which I found was something I do quite frequently in the field. This GLM100-23 Blaz does not save the previous reading - so you end up jotting down the number, which wastes time, and is frustrating when I had gotten used to the GLM 15.