Note 18 - Income Taxes - Summary of Deferred Income Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Compensation and benefit accruals	$ 423,000	$ 328,000
Inventory valuation	889,000	863,000
Federal and state net operating loss carryforwards	35,265,000	35,351,000
Deferred revenue	84,000	21,000
Accounts receivable allowance	18,000	15,000
Defined benefit pension plan	449,000	621,000
Lease liabilities	865,000	1,037,000
Foreign deferred revenue and other provisions	2,367,000	2,548,000
Other	788,000	779,000
Total	41,148,000	41,563,000
Domestic valuation allowance	(38,028,000)	(37,441,000)
Total deferred tax assets	3,120,000	4,122,000
Deferred tax liabilities:
Depreciation	(48,000)	(714,000)
Right-of-use assets, net	(705,000)	(860,000)
Total deferred tax liabilities	(753,000)	(1,574,000)
Net deferred tax asset	$ 2,367,000	$ 2,548,000