Cash and cash equivalents Marketable securities Accounts receivable, net of allowance for doubtful accounts of $111 at April 30, 2023 and April 30, 2022 Contract assets Inventories, net Prepaid income taxes Prepaid expenses and other Total current assets Property, plant, and equipment, net Goodwill Cash surrender value of life insurance Other assets Total assets Identifiable Assets Accounts payable – trade Accrued liabilities Total current liabilities Deferred compensation Total liabilities Contingencies (Note 16) Preferred stock - $1.00 par value; authorized 600 shares, no shares issued Preferred stock, par value (in Dollars per share) Preferred stock, shares authorized Preferred stock, shares issued Common stock - $1.00 par value; authorized 20,000 shares, 9,374 shares issued and 9,373 shares outstanding at April 30, 2023; 9,298 shares issued and 9,297 shares outstanding at April 30, 2022 Common stock, shares authorized Additional paid-in capital Accumulated deficit Common stock reacquired and held in treasury - at cost (1 share at April 30, 2023 and April 30, 2022) Accumulated other comprehensive income (loss) Total stockholders’ equity Balance Balance Total liabilities and stockholders’ equity Revenues Revenues Revenue Cost of revenues Gross margin Selling and administrative expenses Research and development expenses Operating loss Operating Income (Loss) (Loss) income on Investments Interest expense Other income (expense), net Loss before provision from income taxes Provision from income taxes Total provision Net loss Net loss Net loss Basic and diluted loss per share (in Dollars per share) Change in market value of marketable securities before reclassification, net of tax Items of other comprehensive income (loss) before reclassification, net of taxes Total unrealized gain (loss) on marketable securities, net of tax Comprehensive loss Depreciation and amortization Provision for losses on accounts receivable, inventories, other assets and warranty reserve Loss (gain) on marketable securities Loss on sale of fixed and other assets, net Employee benefit plans expense Employee Benefits and Share-Based Compensation Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Accounts receivable Contract assets Increase (Decrease) in Contract with Customer, Asset Inventories Prepaid expenses and other Other assets Accounts payable - trade Accrued liabilities Loss provision accrual Income taxes refundable Other liabilities Net cash provided by operating activities Purchase of marketable securities Proceeds from sale or redemption of marketable securities Capital expenditures Net cash provided by (used in) investing activities Net cash used in financing activities Net increase in cash and cash equivalents Cash and cash equivalents at beginning of year Cash and equivalents at end of year Interest Income taxes Balance (in Shares) Balance (in Shares) Contribution of stock to 401(k) plan Stock Issued During Period, Value, Employee Benefit Plan Contribution of stock to 401(k) plan (in Shares) Stock Issued During Period, Shares, Employee Benefit Plan (in Shares) Stock-based compensation expense Stock-based compensation expense (in Shares) Exercise of stock options and stock appreciation rights - net of shares tendered for exercise price Exercise of stock options and stock appreciation rights - net of shares tendered for exercise price (in Shares) Options, Shares Exercised (in Shares) Equity Components [Axis] Segments [Axis] Accounting Standards Update [Axis] Product and Service [Axis] Basic EPS Shares outstanding (weighted average) Diluted EPS Shares outstanding Raw Materials and Component Parts Work in Progress Finished Goods Buildings and building improvements Machinery, equipment and furniture Less accumulated depreciation Total lease liabilities Present value of future lease payments Total lease payments Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Financial Instrument [Axis] Fair Value, Less than 12 months Unrealized Losses, Less than 12 months Fair Value, Morethan 12 months Unrealized Losses, More than 12 months Fair Value Unrealized Losses Vacation and other compensation Incentive compensation Payroll taxes Warranty reserve Commissions Other Award Type [Axis] Federal State Current provision Federal State Deferred tax provision Statutory rate State and local tax Valuation allowance on deferred tax assets Nondeductible expenses Uncertain tax positions Nontaxable life insurance cash value increase Tax credits Change in tax rate Other items Employee benefits Inventory Accounts receivable Tax credits Other assets Capital Loss carry-forward Net operating loss carryforwards Total deferred tax asset Property, plant and equipment Other liabilities Deferred state income tax Net deferred tax asset Valuation allowance Balance at the beginning of the fiscal year Balance at the end of the fiscal year Lapse in statute of limitations Geographical [Axis] Balance at beginning of year Balance at end of year Warranty costs incurred Product warranty accrual Total other comprehensive income (loss), net of taxes Other comprehensive income (loss), net of tax Document Type Document Annual Report Current Fiscal Year End Date Document Period End Date Document Fiscal Year Focus Document Transition Report Entity File Number Entity Registrant Name Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Address, Address Line One Entity Address, City or Town Entity Address, State or Province Entity Address, Postal Zip Code City Area Code Local Phone Number Title of 12(b) Security Trading Symbol Security Exchange Name Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Entity Emerging Growth Company ICFR Auditor Attestation Flag Document Financial Statement Error Correction [Flag] Entity Shell Company Entity Public Float Entity Common Stock, Shares Outstanding Auditor Name Auditor Location Auditor Firm ID Amendment Flag Document Fiscal Period Focus Entity Central Index Key