SEGMENT INFORMATION - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Revenue	$ 28,130		$ 33,991		$ 54,767	$ 63,815
Cost of revenue	16,157		20,194		31,738	36,942
Other divisional costs	9,403		10,091		19,826	19,378
Division operating income (loss)	2,570		3,706		3,203	7,495
Amortization of acquired intangible assets	850		897		1,663	1,492
Restructuring costs	216		0		529	0
Corporate expenses	2,431		2,473		4,819	5,175
Operating (loss) income	(927)		336		(3,808)	828
Interest expense	(119)		(253)		(271)	(393)
Other income	463		213		707	648
(Loss) earnings before income tax (benefit) expense	(583)		296		(3,372)	1,083
Depreciation	314		356		630	629
Amortization of deferred compensation related to stock-based awards	435	$ 423	564	$ 349	858	913
Capital expenditures	462		316		691	656
Total assets	149,653		160,554		149,653	160,554	$ 152,288
Corporate & Other
Segment Reporting Information [Line Items]
Amortization of acquired intangible assets	850		897		1,663	1,492
Restructuring costs	216				529
Corporate expenses	2,431		2,473		4,819	5,175
Operating (loss) income	(3,497)		(3,370)		(7,011)	(6,667)
Interest expense	(119)		(253)		(271)	(393)
Other income	463		213		707	648
(Loss) earnings before income tax (benefit) expense	(3,153)		(3,410)		(6,575)	(6,412)
Depreciation	39		22		74	43
Amortization of deferred compensation related to stock-based awards	200		411		549	687
Capital expenditures	366		71		373	76
Total assets	1,475		1,599		1,475	1,599
Electronic Test | Operating Segments
Segment Reporting Information [Line Items]
Revenue	13,733		16,159		26,992	27,275
Cost of revenue	7,418		9,462		14,731	15,008
Other divisional costs	4,755		4,954		10,020	8,711
Division operating income (loss)	1,560		1,743		2,241	3,556
Operating (loss) income	1,560		1,743		2,241	3,556
(Loss) earnings before income tax (benefit) expense	1,560		1,743		2,241	3,556
Depreciation	152		154		306	242
Amortization of deferred compensation related to stock-based awards	86		53		140	106
Capital expenditures	63		106		197	142
Total assets	76,259		81,668		76,259	81,668
Environmental Technologies | Operating Segments
Segment Reporting Information [Line Items]
Revenue	7,215		8,273		13,483	15,101
Cost of revenue	4,534		5,016		8,697	9,549
Other divisional costs	2,070		2,264		4,430	4,544
Division operating income (loss)	611		993		356	1,008
Operating (loss) income	611		993		356	1,008
(Loss) earnings before income tax (benefit) expense	611		993		356	1,008
Depreciation	62		80		127	144
Amortization of deferred compensation related to stock-based awards	81		48		49	86
Capital expenditures	24		122		106	351
Total assets	21,944		21,827		21,944	21,827
Process Technologies | Operating Segments
Segment Reporting Information [Line Items]
Revenue	7,182		9,559		14,292	21,439
Cost of revenue	4,205		5,716		8,310	12,385
Other divisional costs	2,578		2,873		5,376	6,123
Division operating income (loss)	399		970		606	2,931
Operating (loss) income	399		970		606	2,931
(Loss) earnings before income tax (benefit) expense	399		970		606	2,931
Depreciation	61		100		123	200
Amortization of deferred compensation related to stock-based awards	68		52		120	34
Capital expenditures	9		17		15	87
Total assets	$ 49,975		$ 55,460		$ 49,975	$ 55,460