Note 4 - Other Accrued Liabilities - Other Accrued Liabilities (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Equipment maintenance and upgrades, non-related party	$ 0	$ 367,000
Insurance	591,000	340,000
Professional services	92,000	90,000
Operating costs	539,000	397,000
Other	322,000	311,000
Total other accrued liabilities	$ 1,544,000	$ 1,505,000