An "Axomat 4" is not a colour enlarger, but an "Axomat 4 Colour" looks like it has a different (more horizontal than vertical) head on it. A google image search shows they seem to have wheels on the front; make sure those are present when you buy, and preferably test the enlarger by turning it on and watching the colour change when you adjust the wheels.
I would also suggest you buy an enlarger that can do medium format, preferably 6x7. They're just as common and cheap, often more sturdy (prints are not softened as easily by slight vibrations in your house), and you can step up to a larger format without replacing the enlarger.
Clean the colour filters gently with lint-free wet-wipes when you get it; they get quite dusty which can cause problems. They're very thin glass though; do not break them or scrub the dichroic coatings off!