I wonder if Spring was the last issue if that means they are no longer publishing?
It was. But Hannah, who runs the Catalina Yachts Store, a separate venture from CY itself, has indicated she will pursue publishing an online-only version most likely in the spring.
See this post:
Latest News About Catalina Mainsheet
Just "catalina" produced parts will be harder/impossible to come by. Unless the company relaunches, which I surely hope happens
It most likely will NOT happen. I have been the C34 Association Secretary for 27 years and have owned Catalina boats since 1983. Recent reporting, not only on boating forums, but in business press, explains the demise of the company. After Frank Butler died a few years ago, the company continued, to eventually be purchased by one Michael Reardon, who professed boat-building knowledge, but turned out to be a shyster, a venture capitalist who has defaulted on the payments of the deal he worked out with CY. It's in the courts now. CY as we've known it since Frank began it in the 60s/70s, is gone, its workers laid off and disappearing. It was a great run, but nothing lasts forever. I read some joker who said this on a boating forum: "Frank should have had a succession plan." A joker because Frank did, but he couldn't force his successors to not sell, or to not sell to a lying shyster.
In addition to Garhauer, there is a company called Catalina Direct, and you should get to know of their outstanding products. Bookmark their home page.
Companionway stairs are a candidate for you to find a good LOCAL woodworker. It sure ain't boat-specific.

Tillers are available from most chandleries, like WM (yuck!), Defender, Hamilton in Canada and, GASP! Catalina Direct.
Most every Catalina model has an active owners association, usually found by
www.c or catalina xyz. org, .com or .net. Search engines find this for the C27:
Catalina27.net - Specs, tech, history, and more Sometimes later models of a certain size Catalina don't have their own associations, piggybacking on earlier models. Some only have Google or Yahoo groups. Sometimes you can find the links by searching "CatalinaXYZ owners manual." I know you have one, but an online one you could download to your computer or phone or tablet would avoid the dreaded "But I left the manual at home!" or "...on the boat!" panic post on this or other boating forums.
Keep coming back here, there are a great bunch of helpful skippers and nice people. Glad you found us.