Note 14 - Guarantees - Changes in Accrued Warranty (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 24, 2022	Sep. 25, 2021	Sep. 24, 2022	Sep. 25, 2021
Balance at beginning of period		$ 7,015	$ 7,541	$ 7,691	$ 6,382
Warranty expense accruals		2,090	4,148	6,733	9,800
Warranty payments		(2,605)	(3,005)	(7,924)	(6,553)
Liability transferred (1)	[1]	0	0	0	(945)
Balance at end of period		$ 6,500	$ 8,684	$ 6,500	$ 8,684

[1] Warranty liability transferred in connection with the sale of our PCB Test business.