Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Cash flows from operating activities:
Net (loss) income	$ (8,663,000)	$ 680,000
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	3,025,000	3,301,000
Non-cash lease expense	(16,000)	(281,000)
Provision for losses on accounts receivable, inventories, other assets and warranty reserve	328,000	(117,000)
Gain on marketable securities	(6,000)	(28,000)
Loss on sale of fixed and other assets, net	163,000	39,000
Loss on impairment of Morion	796,000	0
Employee benefit plans expense	842,000	1,495,000
Stock-based compensation expense	247,000	273,000
Changes in operating assets and liabilities:
Accounts receivable	1,574,000	(752,000)
Contract assets	2,306,000	(2,180,000)
Inventories	(464,000)	3,002,000
Prepaid expenses and other	(171,000)	714,000
Other assets	5,541,000	(584,000)
Accounts payable - trade	(1,000)	(205,000)
Accrued liabilities	(1,355,000)	765,000
Contract liabilities	1,526,000	7,185,000
Loss provision accrual	4,185,000	(690,000)
Income taxes refundable	175,000	405,000
Other liabilities	(5,996,000)	(865,000)
Net cash provided by operating activities	4,036,000	12,157,000
Cash flows from investing activities:
Purchase of marketable securities	(2,511,000)	(2,452,000)
Proceeds from sale or redemption of marketable securities	2,089,000	2,498,000
Capital expenditures	(1,860,000)	(1,239,000)
Net cash used in investing activities	(2,282,000)	(1,193,000)
Cash flows from financing activities:
Repayment of PPP loan	0	(4,965,000)
Net cash used in financing activities	0	(4,965,000)
Net increase in cash and cash equivalents	1,754,000	5,999,000
Cash and cash equivalents at beginning of year	9,807,000	3,808,000
Cash and equivalents at end of year	11,561,000	9,807,000
Cash paid during the year for:
Interest	77,000	123,000
Income taxes	15,000	0
Cash refund during the year for:
Income taxes	$ 183,000	$ 477,000