Note 8 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Inventories	$ 202,000	$ 254,000
Accrued employees' compensation and benefits costs	316,000	362,000
Postretirement adjustment (accumulated other comprehensive loss)	566,000	635,000
Accrued litigation settlement	128,000	39,000
State credit carryforwards	157,000	177,000
Federal credit carryforwards	302,000	0
Federal net operating loss carryforward	482,000	1,493,000
Bad debt reserve	3,000	26,000
Warranty reserve	70,000	114,000
Research and experimentation expenses	2,217,000	751,000
Customer accruals	156,000	344,000
Sec 163(j) disallowed interest	46,000	83,000
Other	1,000	1,000
Total deferred tax assets	4,646,000	4,279,000
Valuation allowance	(3,727,000)	(3,145,000)
Net deferred tax assets	919,000	1,134,000
Prepaid expenses	(78,000)	(71,000)
Property, plant and equipment	(841,000)	(853,000)
Other receivable - insurance proceeds	0	(210,000)
Total deferred tax liabilities	(919,000)	(1,134,000)
Net deferred tax assets	$ 0	$ 0