Before you get the idea from this thread that a Beseler is an unadulterated POS relative to, say, a Saunders, a couple of things should be mentioned about using lasers to check alignment and how depth of field and depth of focus practically affect the need for precision alignment. A laser device like the Versalab, if not defective itself, allows you to check for parallelism of the three planes of an enlarger (base, negative and lensboard). If the reflected dot lines up with the bullseye, you have perfection; but if doesn't, what does that signify? The answer depends on negative size, aperture of lens and lens to negative and lens to baseboard distances, as is really well explained in the book Way Beyond Monochrome for example. However, given that we are usually enlarging rather than reducing, the two winners in the critical parallelism category are the lensboard and the negative stage relative to one another; it is far less critical that they both be parallel to the baseboard down where the print lays.
The negative holder and the lensboard stage on the Beseler are castings that slide relative to each other up and down an accurately machined and ground bar of steel. If the castings were beefy enough this would be an ideal design. They are not beefy enough as they are made of rather thin aluminum or pot metal, but they are usually good enough. Once you put the adjustable lenboard on, you can quickly adjust the two planes to be parallel and they will remain so. This presupposes that the stages are in good working order with their bearing surfaces (brass and later plastic) properly tightened with those little screws. As discussed above, this is the critical part of alignment and Beseler did a good job of handling this issue. Less well handled is keeping this whole fixture parallel to the base as the motor whirs the whole assembly up and down. Suffice it to say that the engineering on this aspect is not very good, depending on a fairly flexible frame work of thin steel frame and struts. But this is less critical as the depth of focus at the paper can be half an inch. The laser doesn't know which measurement is more critical and will scare you unnecessarily as you watch the red dot wander around. So before you haul your 45M away or put a sheet over it in disgust, get the adjustable lensboard and relax.
Hypocrite alert: I mentioned before that I have both a 45M and a Saunders. In my darkroom, currently set up, is the Saunders, but if I had more room they would be side by side. However, I bought the Saunders (at many times the expense of my $50 45M from the '50's) for the convenience of the VCCE head and the fine focus + extension - before I bought the Versalab and got hypnotized by red dots.