Open enrollment for Medicare begins Tuesday and lasts through December 7. Beneficiaries are encouraged to compare their current plans with other plans on the market. Senior Health Insurance Benefits Assistance Medicare program analyst Lisa Emerson says there are more than two dozen plans to sift through. Oregonians can find assistance online at SHIBA.oregon.gov, or by calling 1-800-722-4134. Emerson says the assistance program is always looking for volunteers.