7. Property, Plant and Equipment and Leases (Details) - Schedule of Property, Plant and Equipment - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Schedule of Property, Plant and Equipment [Abstract]
Buildings and building improvements	$ 2,692	$ 2,790
Machinery, equipment and furniture	57,157	57,503
	59,849	60,293
Less, accumulated depreciation	(46,811)	(46,166)
	$ 13,038	$ 14,127

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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