Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022
Cash flows from operating activities:
Net loss	$ (5,501,000)	$ (8,663,000)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	2,434,000	3,025,000
Non-cash lease expense	(39,000)	(16,000)
Provision for losses on accounts receivable, inventories, other assets and warranty reserve	567,000	328,000
Loss (gain) on marketable securities	784,000	(6,000)
Loss on sale of fixed and other assets, net	34,000	163,000
Loss on impairment of Morion	0	796,000
Employee benefit plans expense	1,054,000	842,000
Stock-based compensation expense	197,000	247,000
Changes in operating assets and liabilities:
Accounts receivable	(332,000)	1,574,000
Contract assets	(1,110,000)	5,246,000
Inventories	(1,220,000)	(464,000)
Prepaid expenses and other	91,000	(171,000)
Other assets	(366,000)	5,541,000
Accounts payable - trade	384,000	(1,000)
Accrued liabilities	217,000	(1,355,000)
Contract liabilities	7,487,000	(1,414,000)
Loss provision accrual	(2,699,000)	4,185,000
Income taxes refundable	239,000	175,000
Other liabilities	(1,046,000)	(5,996,000)
Net cash provided by operating activities	1,175,000	4,036,000
Cash flows from investing activities:
Purchase of marketable securities	(1,382,000)	(2,511,000)
Proceeds from sale or redemption of marketable securities	10,967,000	2,089,000
Capital expenditures	(918,000)	(1,860,000)
Net cash provided by (used in) investing activities	8,667,000	(2,282,000)
Cash flows from financing activities:
Payment of Dividend	(9,354,000)	0
Net cash used in financing activities	(9,354,000)	0
Net increase in cash and cash equivalents	488,000	1,754,000
Cash and cash equivalents at beginning of year	11,561,000	9,807,000
Cash and equivalents at end of year	12,049,000	11,561,000
Cash paid during the year for:
Interest	129,000	77,000
Income taxes	7,000	15,000
Cash refund during the year for:
Income taxes	$ 176,000	$ 183,000