Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Deferred Tax Assets:
Net operating loss	$ 10,186	$ 12,682
Credit carryforwards	1,332	1,598
Deferred compensation	1,897	2,095
Uniform capitalization and inventory	1,506	1,222
Stock-based compensation	1,083	921
Reserve for accrued employee benefits	872	718
Warranty accrual	559	579
Accrued legal	161	130
Postretirement benefits liability	0	156
Other	345	326
Deferred tax assets	17,941	20,427
Deferred Tax Liabilities:
Depreciation and amortization	(3,764)	(4,404)
Retention and other	(1,229)	(886)
Deferred tax liabilities	(4,993)	(5,290)
Less: valuation allowance	(3,787)	(10,498)
Net deferred income tax asset	$ 9,161	$ 4,639