Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Apr. 30, 2020	$ 9,164	$ 56,914	$ (12,137)	$ (195)	$ 490	$ 54,236
Balance (in Shares) at Apr. 30, 2020	9,163,940			42,696
Contribution of stock to 401(k) plan	$ 26	325		$ 68		419
Contribution of stock to 401(k) plan (in Shares)	26,192			(14,926)
Stock-based compensation expense	$ 4	269				$ 273
Stock-based compensation expense (in Shares)	4,200
Exercise of stock options and stock appreciation rights - net of	$ 32	(153)		$ 121
Exercise of stock options and stock appreciation rights - net of (in Shares)	31,936			(26,395)		247,500
Other comprehensive income (loss), net of tax					(199)	$ (199)
Net income (loss)			680			680
Balance at Apr. 30, 2021	$ 9,226	57,355	(11,457)	$ (6)	291	$ 55,409
Balance (in Shares) at Apr. 30, 2021	9,226,268			1,375		9,225,000
Contribution of stock to 401(k) plan	$ 44	382				$ 426
Contribution of stock to 401(k) plan (in Shares)	44,224
Stock-based compensation expense	$ 16	231				$ 247
Stock-based compensation expense (in Shares)	16,216
Exercise of stock options and stock appreciation rights - net of	$ 12	(12)
Exercise of stock options and stock appreciation rights - net of (in Shares)	11,470					42,875
Other comprehensive income (loss), net of tax					(731)	$ (731)
Net income (loss)			(8,663)			(8,663)
Balance at Apr. 30, 2022	$ 9,298	$ 57,956	$ (20,120)	$ (6)	$ (440)	$ 46,688
Balance (in Shares) at Apr. 30, 2022	9,298,178			1,375		9,297,000