Note 4 - Other Accrued Liabilities - Other Accrued Liabilities (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Equipment maintenance and upgrades	$ 6,000	$ 367,000
Insurance	105,000	340,000
Professional services	194,000	90,000
Operating costs	552,000	397,000
Other	283,000	311,000
Total other accrued liabilities	$ 1,140,000	$ 1,505,000