With regards to aligning, mine is a Durst M605 and I'm not sure it is really prone to getting out of alignment to begin with, unless you go fiddling with the bellows, but actually aligning it is as simple as setting it to zero at a couple of points - the tilt head & the bellows. I mean it's not that complicated an enlarger, know what I mean?
Greetings. Absolutely all enlargers need to be aligned. The original factory/manufacturer machined settings are only approximate, and always need to be corrected over time and use. The negative stage needs to be parallel to the easel. And likewise, the lens stage needs to be parallel to the easel. Without verifying your enlarger alignment, you cannot possibly achieve the optical performance your enlarging lens was designed for.
With your very nice Durst M605, it is a relatively easy task. You need to first align the negative stage parallel to the easel using the enlarger head focusing lock knob. Loosen the enlarging head lock knob and you can move the head and negative stage incrementally and minutely side to side from the factory set detente position.
Once you have aligned the negative stage, you then need to align the lens stage. On your M605 this can be accomplished by loosening the lens stage bellows knob and moving the lens stage minutely side to side from the factory detente position in order that the lens stage is parallel to the easel.
You may also need to use thin mylar adhesive strips on the top of your Durst siriotub lensboard to achieve perfect lens stage alignment.
In any case, I use a laser alignment tool, the versalab parallel, to quickly and accurately align my enlargers, one of which is a Durst M605 Classic. If you can take the time, and expense, to check your own M605 enlarger alignment, you likely will be surprised at how much it can be improved? Good Luck.