Q: Fixing corrupted Calendar on iMac

My iMac Calendar has stopped showing appointments, worked fine until a few days ago. If I add a new event to the iMac calendar nothing shows on the iMac but the events show (through iCloud) on my MacBook Air. If I add to MacBook Air calendar it shows fine there and on other devices (iPad etc) but not on the iMac.  The problem started with a few of my iCloud calendars but is now happening with all and with a synced gmail calendar. Old events are still visible. I tried deleting plist it didn't help. Can I delete and reinstall Calendar or do I have to wipe the whole machine, running Yosemite on all machines?