GOODWILL AND OTHER INTANGIBLE ASSETS - Other intangible assets - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other intangible assets:
Cost	$ 10,840,000	$ 12,466,000
Accumulated amortization	4,614,000	4,207,000
Net book value	6,226,000	8,259,000
Customer relationships [Member]
Other intangible assets:
Cost	6,502,000	7,825,000
Accumulated amortization	3,034,000	2,724,000
Net book value	$ 3,468,000	$ 5,101,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 7 months 6 days	8 years 8 months 12 days
Trademarks and trade names one [Member]
Other intangible assets:
Cost	$ 2,187,000	$ 2,375,000
Accumulated amortization	0	0
Net book value	$ 2,187,000	$ 2,375,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years 6 months	11 years 6 months
Trademarks and Trade Names Two [Member]
Other intangible assets:
Cost	$ 200,000	$ 200,000
Accumulated amortization	59,000	45,000
Net book value	141,000	155,000
Engineering drawings [Member]
Other intangible assets:
Cost	330,000	330,000
Accumulated amortization	239,000	225,000
Net book value	$ 91,000	$ 105,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 1 month 6 days	7 years 1 month 6 days
Non-compete agreements [Member]
Other intangible assets:
Cost	$ 335,000	$ 331,000
Accumulated amortization	266,000	235,000
Net book value	$ 69,000	$ 96,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years	3 years 8 months 12 days
NUMATX[Member]
Other intangible assets:
Cost	$ 1,286,000	$ 1,405,000
Accumulated amortization	1,016,000	978,000
Net book value	$ 270,000	$ 427,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years 2 months 12 days	7 years 1 month 6 days