I have one of those, very similar if not identical (I’d have to go and check). i haven’t had to make any adjustments to mine but if I did i would start by removing the top plate and looking to see if there is any clue.

Be aware that these levels are so sensitive that mine would move if you put it on the floor then walked around to the other side. Double-check that there is no burr or debris that it might be resting on and that there are no dings in the bottom edges from poor handling. You can take a hard stone and gently stone the bottom face a few strokes then carefully check for shiny spots. These will affect the reading of the level.

Noel, could well be. Netherton was the location of he WW2 shadow factory set up to produce Sabre engines, and later (under English Electric’s control) built Deltics. My father worked there as an inspection engineer from its wartime setup (1942/43 ?) until about 1970/72.

Wonder if he ever handled that particular level!!!

Right, having inspected the one I have here at home I would say that on the side of the level in pic 3 you have a slotted screw with a hex set screw underneath. I think that the slotted screw is a pinch screw for the vial to hold it firm once adjusted. The hex socket screw underneath is the adjuster, it’s probably conical and screwing it inwards lifts that end of the vial. Turn the level over and on the underside you should find a small screw in line with the socket head adjuster screw. I think that this is a locking screw to stop the adjuster screw from moving once it’s been set.

Your adjuster screw looks to be a lot more proud than the one on mine. Perhaps it’s been fiddled with or perhaps the little pinch screw underneath is missing and it’s managed to fall out of adjustment.

Hi, adjusting this type of level is not that easy, but the surface you do it on doesn’t have to be dead level, but it must be flat. Both the surface you use and the level should be in the same room at a constant temperature for at least a couple of hours or more, to stabilise, and you shouldn’t handle the level anymore than needed, and of course the whole affair should be very solid, as even moving your body can affect the readings. Adjustments should be in small stages, and when rotating it to check, it needs to be on the exact same spot as much as possible, as even a few microns can make a difference. I’ve got a level that is 0.0002″/10″ which is a waste of time having really, and is really difficult to calibrate, and even a small change in temperature will alter its reading.

Regards Nick.