Ripples are a common problem when working with epoxy. You can sand it, but you should be in a well-ventilated area and/or wear a mask when you do it. I use a lot of liquidglassepoxyresin.com and I've discovered that if I apply a very thin seal coat on bare wood it helps me to avoid ripples so that I do not have to work so hard at sanding/repairing. I brush on the first coat with a foam brush, let it cure for several hours to get firm, and then I pour the self-leveling flood coat.
Carter makes several styles of guides. Some are Euro style. The ones SCM used on this model had steel blocks for the side guides rather than bearings. The SCM at school has Carter Euro guides but are a major pain to adjust.